What motivates iago to carry out his schemes? is he a devil, madman, or rational human being? from othello.

In The Tragedy of Othello by William Shakespeare, Lago can best be described by irony. He is widely known by his honesty, but is a lying, cunning, revengeful and heartless man. In the play, there is not much explanation as to why he behaves this way other than how he seems to enjoy (or love) being that way.

Because his never-ending need to plot against other people's lives, there is a lot of parallelism between him and the Devil (but not quite). While he gives many excuses as to why he [Lago] hates Othello, none of them are satisfactory and/or stick long enough to be considered as true. 

Therefore, your best answer is a madman.

An inference that can be made is that the princess is bothered about the tiger door. although there are reasons for both this one has a better reason. the princess is not a monster and even if she didn't want to marry this man she wouldn't want him to die. the grudge of death is pretty heavy. unless she has done this before and feels no regret then she wouldn't want to be married to someone of low quality, if he is low quality.