The character of Nero is the last in a series of emperors that are described by Tacitus, and they are each one shown to be worst than the last in terms of their despotism and their level of evil. Nero, from the way that he is described in this ancient text, certainly seems to be far more nefarious compared to his predecessors. Not only does he kill any who oppose him, he is also shown to have incestuous relations with his mother before resolving to kill her because of the power she has over him and is still fighting to maintain. Note how the following quote describes this:
At last, convinced that she would be too formidable, wherever she might dwell, he resolved to destroy her, merely deliberating whether it was to be accomplished by poison, or by the sword, or by any other violent means. Poison at first seemed best, but, were it to be administered at the imperial table, the result could not be referred to chance after the recent circumstances of the death of Britannicus.
Not only does this show him cold-heartedly plotting the exact manner of his own mother's death, it also references past assassinations he has committed. This is an emperor who is shown to have no moral compunctions whatsoever. The manner in which Agrippina finally dies, being killed by sword in her bed, having survived a previous attempt on her life through chance, indicates the way in which Nero feels that he can act in any way he wishes. In moral terms, he is an abomination.