When Drew breaks off his engagement to Nikki, he's terrified to tell his dad the entire episode, especially when his mother reveals his father has been suffering a serious depression the last few months. He finally blurts out the secret though, and while his dad is a little disappointed, he's at least relieved his son didn't marry someone who wasn't right for him. Drew's always had a weird relationship with his dad, so it's nice to see a genuine bonding moment like this. Plus he has a confession too: it turns out he's been milking the depression to get out of yard work.
Throughout the series, Drew and Mimi clearly had a rivalry going on. However, they also knew each other better than most of their friends did and even become in-laws when Mimi marries Drew's brother. In the last season, when it was discovered Drew's brother was having an affair, what does Drew do? He takes Mimi's side.
Many moments in Drew and Kate's relationship, their first kiss, their first time making love, when Drew asks her to marry him, etc.
Drew's had a great relationship with his nephew Gus ever since Drew was in his coma. Ready to give up on life, Drew is prepared to die and he sees his nephew preparing to descend down and be born. It gets a little into Adult Fear when Gus has second thoughts about being born when he sees how rude and boorish Mimi is around Drew but Drew manages to convince him to be born by going into Gus' body to show Mimi's sensitive side. Gus then helps convince Drew that life is still worth living and the two of them go back to their respective bodies together. When Drew wakes up, he greets his newborn nephew like an old friend.