than that, Enfield describes Hyde as possessing a "black sneering coolness" and "carrying it off, sir, really like Satan." While Jekyll is kind, handsome, and warm, Hyde is cruel, odious, and unfeeling. Jekyll enjoys people and their company, especially the company of people he cares for (like Utterson), but Hyde seems to care for nothing and no one but himself. In fact, he is so hateful that he inspires the doctor—a man who has taken an oath to do no harm—to seem to want to murder him.

Further, after Utterson meets Hyde himself, the narrator describes Hyde as

pale and dwarfish, he gave an impression of deformity without any nameable malformation, he had a displeasing smile, he had borne himself to the lawyer with a sort of murderous mixture of timidity and boldness, and he spoke with a husky, whispering and somewhat broken voice; all these were points against him, but not all of these together could explain the hitherto unknown disgust, loathing and fear with which Mr. Utterson regarded him.

Jekyll, of course, is described as being rather tall and handsome. Hyde seems cramped and deformed, by contrast. He seems incredibly unnatural, which, of course, he is, and this sense of his unnaturalness seems to impact everyone who meets him. Human beings are by nature, in this text, comprised of both good and bad parts—capable of being both kind and wicked—and yet this person is only bad and wicked. People seem to sense this right away.

Dr. Lanyon is one of the oldest friends in Dr. Jekyll's circle.

Some of the similarities that both characters share include the fact that they are both medical doctors who are highly respected in London, and each of them has his own views on science and how to approach their practices. They run in similar circles of wealthy, sophisticated, professional men who like the best things in life.

The doctor gave one of his pleasant dinners to some five or six old cronies, all intelligent reputable men, and all judges of good wine.

The key contrasts between Dr. Hastie Lanyon and Dr. Jekyll include that Lanyon, as opposed to Jekyll, is a believer of rational treatments and conventional medicine. He believes in prevention, as most physicians do, and he is quite hands-on with his methodology.

Jekyll, on the other hand, is more of an idealist. After all, isn't he busy preparing a weird concoction to separate his evil side from his good side? That's way against the typical mindset of any man of science.

Yet, there is additional evidence in the novel that shows that the biggest contrast between Jekyll and Lanyon has always been their approach to science. This is found in the letter that Jekyll writes to Lanyon in a cry for help.

DEAR LANYON, You are one of my oldest friends; and although we may have differed at times on scientific questions, I cannot remember, at least on my side, any break in our affection.

Alongside their differences in scientific opinion, we could also add that Lanyon's personality and physical appearance is different from Jekyll's.

Lanyon is described as ruddy, heavy, and with a brash demeanor.

He was a hearty, healthy, dapper, red-faced gentleman, with a shock of hair prematurely white, and a boisterous and decided manner.

Whereas Jekyll is described as decidedly "handsome," with a more peaceful nature and with a disposition for kindness.

He was a large, well-made, smooth-faced man of fifty, with something of a stylish cast perhaps, but every mark of capacity and kindness.

Still, notice that, even after parting ways with Jekyll, he saw Lanyon, of all people, as the only physician who could save him.

In the letter written by Jekyll, it is clear that Jekyll sees in Lanyon someone who was an equal in terms of ability and talents in the medical field.

While the two men argue about how things should be approached, in the end, the idealistic Jekyll falls prey to his own experiment and would obviously reach out to someone whom he would believe to be talented enough, or even more talented than him, to be able to save him from the huge disaster that he gets himself into.

Lanyon, my life, my honour my reason, are all at your mercy; if you fail me to-night, I am lost. You might suppose, after this preface, that I am going to ask you for something dishonorable to grant. Judge for yourself.

With these statements, we could also add that, between the two of them, Lanyon is also more mature and has more common sense than Jekyll.

Lanyon and Jekyll are both medical doctors and old acquaintances. They also have Utterson as a close mutual friend, but beyond this they have little else in common. Lanyon is a stolid conservative type, who believes very much in sticking to the rules in his life and work. Jekyll is the opposite; he is adventurous and imaginative. He seeks after forbidden knowledge, to push limits, break rules.

Lanyon is the voice of convention, the representative of law-abiding society, Jekyll is a romantic, and dangerous Faust-like figure, dabbling in unholy acts in order to pursue his lusts and passions under cover of his second self Hyde. His actions drive a wedge between him and Lanyon, while Utterson tries vainly to mediate between them. Lanyon, in fact, is so appalled when he sees the results of Jekyll’s unholy experiments that the shock literally kills him.

Yet Lanyon and Jekyll are not simple polar opposites. Jekyll repents of his deeds and suffers terribly, as is clear in his confession. His longing for greater knowledge and freedom need not in itself have been a bad thing, the problem is that he was unable to curb the darker side of his nature, which leads to his alter ego Hyde ultimately taking over completely. Jekyll, in his confession, shows the kind of propriety, the concern to maintain social respectability, that is so evident in Lanyon.

Lanyon, meanwhile, is maybe not as narrow-minded and set in his ways as might be thought. When he is about to (unwittingly) witness Hyde’s transformation into Jekyll, Hyde issues a word of warning.

Will you be wise? will you be guided? will you suffer me to take this glass in my hand and to go forth from your house without further parley? or has the greed of curiosity too much command of you?  (chapter 9)

Hyde, then, asks whether Lanyon will be 'wise' and prudent, or not. Lanyon, for once, acts without caution, and decides to see the whole strange business through. He stays to witness Hyde's metamorphosis into Jekyll, which has the effect of almost blasting his senses. However, he does for a moment show the kind of curiosity and interest in unlawful things that Jekyll has in larger doses. It might be that he is not so rigid after all, although it is hard to imagine that he would ever have gone to the kind of lengths that Jekyll does.

Dr. Lanyon and Mr. Utterson are Jekyll's oldest friends. Lanyon and Jekyll are both scientists. Jekyll has a pleasure seeking "gaiety" beneath his grave, serious manner, and Lanyon has a similar personality, though his "boisterous" self is not hidden beneath a facade. Utterson describes him as follows:

a hearty, healthy, dapper, red faced gentleman, with a shock of hair prematurely white, and a boisterous and decided manner.

When Utterson begins to question him about his relationship with Jekyll, Lanyon says he has not seen much of him in the last ten years. He says Jekyll became too "fanciful" for him and began to go "wrong" in his scientific researches.

I would say the main difference between the two is that Lanyon's personality is well-integrated and well balanced—not at war with itself. Lanyon simply accepts his "boisterous" side and has no desire to split off the "partier" from the "scholar." He doesn't push the limits of science as Jekyll does and is happy to live with the conventional restraints of society. He is comfortable in his own skin. In fact, what he learns about his old friend is so shocking it kills this conventional man.

In the novella The Strange Case of Dr. Jekyll and Mr. Hyde, there are quite a few instances of dialogue author Robert Louis Stevenson uses to show us that Dr. Jekyll and Mr. Hyde are two different people yet also the same person.

One of the best examples can be seen the first moment Mr. Utterson, Dr. Jekyll's lawyer, converses with Mr. Hyde. The novella opens with Mr. Enfield sharing a story with Mr. Utterson of Mr. Hyde being seen trampling a child and then agreeing to pay the child's family monetary compensation. After hearing the story, Mr. Utterson felt a strong urge to see Mr. Hyde. The reason behind his strong urge concerns the fact that Dr. Jekyll left in his possession a very strange will stating that, in the event of Dr. Jekyll's death, Dr. Jekyll would leave all of his possessions to Mr. Hyde, but if Dr. Jekyll should disappear, then Mr. Hyde should take the place of Dr. Jekyll. Hearing that Mr. Hyde is a morally questionable person, even a monster, Mr. Utterson becomes very anxious to see what Mr. Hyde is like for himself.

The next evening, Mr. Utterson sees Mr. Hyde about to let himself into Mr. Jekyll's home and approaches him, saying, "I see you are going in ... I am an old friend of Dr. Jekyll's" (Part I). Mr. Hyde's simple response to this statement shows us that he considers himself to be a separate person from Dr. Jekyll: "You will not find Dr. Jekyll; he is from home" (Part I). Mr. Hyde's response would have been impossible if he had thought of himself and Dr. Jekyll as the same person, because surely Mr. Hyde, who is Mr. Jekyll, has just arrived at home.

But Mr. Hyde also next says something that shows the reader Mr. Hyde also understands that he and Dr. Jekyll are deeply connected, so connected that Mr. Hyde knows what Dr. Jekyll has done and would do. The connection is shown when Mr. Hyde asks how Mr. Utterson knew of Mr. Hyde's name. Mr. Utterson evasively replies, "We have common friends," and suggests Dr. Jekyll as their common friend (Part I). However, Mr. Hyde's response to Mr. Utterson's reply is to grow angry and say, "He never told you ... I did not think you would have lied," showing us just how connected Mr. Hyde is to Dr. Jekyll (Part I).

Stevenson's use of dialogue to show the reader both the separateness and the connection between the two characters helps serve to foreshadow future revelations. Hence, by the time the reader hears Dr. Jekyll confess that, though they look and behave very differently, he and Mr. Hyde are two sides of the same coin, the "good" side and the "evil" side, the reader is not that surprised due to the foreshadowing clues.

Though a relatively minor character in the story, Lanyon plays an important part in acting as a foil to Dr. Jekyll. This means that he's there to bring out certain characteristics in Jekyll. Foremost of these is Jekyll's willingness to indulge in all manner of weird scientific experiments, such as the one that causes him to turn into his crazed alter-ego, Mr. Hyde.

Lanyon would never dream of carrying out such experiments, not in a million years. He's a rationalist, a skeptic, a man who believes that being a doctor entails a willingness to accept material explanations of all phenomena. Not surprisingly, he speaks dismissively of Jekyll's experiments, regarding them as "unscientific balderdash".

Jekyll, on the other hand, though also a doctor, is willing to push the frontiers of knowledge, indulging in experiments that are more mystical than strictly scientific. Unfortunately, these experiments, like Frankenstein's, are ultimately of no benefit to humankind; in fact, they're actually a threat to humankind.

Yet even the normally skeptical Lanyon is forced to conclude that Jekyll's experiments have revealed a hitherto unknown realm of reality, albeit a very dark, disturbing realm. That even an arch-rationalist such as Lanyon should eventually recognize the truth of what Jekyll has revealed gives a certain credibility to the mad scientist's discoveries that they would otherwise patently lack.

Dr. Lanyon is a somewhat minor character in The Strange Case of Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson, but important to the progress of the narrative. He is a close friend of both Gabriel John Utterson and of Dr. Jekyll, but is medically conservative and disapproves of Dr. Jekyll's experiments. As Mr. Utterson strives to solve the mystery of Hyde, he approaches Lanyon, but Lanyon at first prevaricates. When Dr. Jekyll accuses Lanyon of being a "hide-bound pedant", this makes Utterson think that their falling out was merely over a point of science. As we discover later in the story, after the death of Lanyon, Lanyon helped Jekyll by bringing him the potion that turned him back from Hyde into Jekyll but disapproves of Jekyll's work. 

Lanyon is not a particularly well-rounded character in the story. In contrast to both Jekyll and Utterson, he is intended to represent an ordinary, rather conventional person appalled by Jekyll's experiments. He seems pleasant, responsible, and kind, willing to help out an old friend, but otherwise is not really presented in detail but merely acts as a vehicle for the plot.