How does the scene between Portia and the Prince of Morocco further Portia’s characterization?It is in Act II of the play.

Portia flatters Prince Morocco that he looks as "ari as any comer I have looked on yet," yet we doubt her (2.1.20-21). But she would not like him, I would guess, not just because of his color (in this play that does explore prejudice) but because he is so insufferably vain.  He is quick to tell her that "I swear /The best regarded virgins of our clime/ Have loved it [his color] too (2.1.8-10.) Before he chooses the casket he continues to brag about his exploits, comparing himself, for example, to a Persian ruler and Hercules (25-32). Interestingly, we do not see him again until 2.7 (six scenes later), when he finally makes his choice. In these scene we learn about the avariciousness of Shylock. Then, when Morocco chooses, we learn again he is vain and too confident by the casket he chooses: "in love I do deserve" (2.7.38).  Portia is obedient, however, for she is fully prepared to follow her father's orders even if this vain, unpleasant man chooses correctly. When she says "Let all of his complxion choose me so" she comments on his character every bit as much as his color, and we are uncertain as to which offends her more.