The set-up for the season includes a backstory about Ben, a boy who seeks out Charlie for makeout sessions but then acts cruelly towards him in public.
The secret meetings come to a head when Charlie decides he's had enough of this treatment and tries to break things off with Ben, only to have the older boy push him against the wall and kiss him against his will. Nick arrives to the scene, and pulls Ben off of Charlie.
This is one of the first times we see Nick go out of his way to make sure Charlie is OK — and it's the first time Charlie gets the feeling that maybe Nick could have feelings for him in return.
Nick gives Charlie a few pats on the arm instead of hugging him in this moment, but it's the scene that cements their close friendship (which serves as the foundation for their future romantic relationship).