I need to write a monologue for Alex Robbins. What should I say, how will he try to help Rufus?
The question of how Alex is going to help Rufus was just asked a few days ago. Here's a link.
If you look at that answer, it should help you be able to write a monologue for Alex.
You can see that Alex feels that the gang members' problems are caused by them feeling that they are inadequate and powerless. You can also see that he thinks that Rufus, at least, is stupid when he considers engaging in violence.
So you should write a monologue that talks about that kind of thing -- you should have him explain his vision of why the gang members act like they do and what he thinks he can do about it.