The monster, in Mary Shelley's Frankenstein, obsessively follows Victor. One could justify two different reasons for the monster's trailing of his "father."
First, the monster could be playing a game with Victor. By forcing Victor to constantly look over his shoulder, the monster is able to possess a power over him. No longer is the monster at Victor's mercy; instead, Victor is at the monster's.
“Slave, I before reasoned with you, but you have proved yourself unworthy of my condescension Remember that I have power; you believe yourself miserable, but I can make you so wretched that the light of day will be hateful to you. You are my creator, but I am your master;—obey!”
The monster's naming of Victor as his slave allows the monster to possess the power to do with Victor what he desires.
Outside of this, one could also justify that the monster's following of Victor could represent to love he has for his "father." In the end, when Victor has died, the monster declares his love for his father.
Oh, Frankenstein! generous and self-devoted being! what does it avail that I now ask thee to pardon me?...When I first sought it, it was the love of virtue, the feelings of happiness and affection with which my whole being overflowed, that I wished to be participated.
Therefore, the following of Victor could be seen as a game played by the monster in order to make Victor pay for alienating him, or the following of Victor could illustrate the love the monster has for him (and is just unable to show given he does not know how to love).