Declan is the sort of guy who changes dramaticaly depending on who he is talking to. In this crowd, he would be calm, friendly and kind, but when facing an enemy - he would find it easy to flip and knock a few heads. Obviously everyone in the group, he would be friendly towards, but he'd probably have slightly different relationships for each one. I'll just leave this here...
>I think he would have quite a brother-from-another-mother vibe with Corey as they seem quite similar in some ways, so they could be good friends. I think Corey is probably less of a loose cannon and there may be one or two occasions where he will have to hold Declan back and stop him from getting killed or something.
>He would probably have an odd relationship with the people younger than him, as they may remind him slightly of his deceased brother. I think he would be protective of them, in a way, keeping their backs, as if it was making up for the mistakes he made with his brother.
>He could relate to Riley, as, despite the fact he haz a large family, he recieved minimal affection from his parents in his upbringing and only had a real connection with one or two or his siblings, who he had to look after himself. Basically, he didn't have anyone to watch over him when he was young.
>Both he and Madison have earned a wage doing things some would call a little unorthodox, and seen some hardships along the way, so that could be a talking point.
>Declan has dealt with depression stemming from loss in his life, just like Ara, so he would see her as someone he could relate to. Another factor would be the point that they are both immigrants in one way or another, and are both pretty new to the country.