Since that night, Chuck and Serena stayed away from each other, but Serena obviously has forgiven him.
Their relationship drastically changes in the second half of Season 1 when Bart Bass and Lily van der Woodsen (at the time) got married, thus forcing both Serena and Chuck to get along with each other as step-siblings.
After many seasons, Chuck plays an integral role as Serena's enabler & mentor during her high school, romantic & College choices, and schemes.
Both Serena and Chuck are forced to act on their best behaviors during a party by their respective sole parents for family reconciliation and investors of Bass Industries respectively.
However, Serena previously and co-currently at the time kept receiving cryptic and threatening gifts who she blamed for Chuck as the culprit.
In Season 1, Chuck tried to sexually assault Serena.
This was due, at the time, of Chuck's predatory and innate abandonment issues from a result of his fractured family.
In Season 1 both Serena and Chuck often scheme together along with Nate and Blair in a group called the NJBC (The Non Judging Breakfast Club).
Serena has demonstrated an almost unilateral support, except for the few times with Louis, for Chuck and Blair to get together in a relationship.In concurrence, Chuck seems to easily display his inner passions and thoughts to Serena without any repercussion or judgement; mainly due to their platonic nature.As the series progresses, Chuck and Serena share a very close relationship and often confide in each other.Serena is obligated to behave well for Lily's sake because of her effort for a mother-daughter reconciliation.Whereas, Chuck is told by Bart to behave for public image as investors are watching their values as a family.They enjoy spending time together along with their best friends, Blair and Nate.