Kimi is Chuckie's adoptive step-sister. Chuckie is overprotective with her a lot and if she does something he has to know about it. Kimi doesn't understand why he's so overprotective and she's so under protective. Although when he's bad she manages to keep it a secret but Chuckie has to pay her back as seen in Chuckie had a secret instant and he claimed "I was baking waffles!" And finally close to the end they confronted each other in the episode and live in front of all the popular kids at school she told the instant to the whole school and they laughed then Chuckie said 2 quotes I remember "well she still sucks her thumb" and "she asked Santa for a cell phone 3 years in a row!" and Kimi admitted she did and yelled to the crowd as she cried "I wish I never started this dumb petition anyway!" which made Chuckie feel bad.
Kimi Finster and Tommy Pickles have had so much history together depending on the fans, like in TP+KF, where it is revealed that Kimi used to have a crush on Tommy. Kimi is viewed by some as a copy of Tommy or as a parallel of him and Chuckie has even commented on this too. Kimi cares for Tommy and his brother Dil. Kimi still enjoys hanging out with Tommy and they share some interests like their love for Chuckie & Dil.
Kimi and Phil have little interaction in AGU! but are still close friends. When Chuckie wanted to renovate Kimi's room as a surprise, Phil helped and appeared to work harder then most of them. Kimi & Phil were closer in the original Rugrats, however they are still friends. Kimi doesn't have much in common with Phil; she thinks he is disgusting.
Kimi and Lil are best friends and have always been very close and got even closer as they grew up. They both were the only two girls in their group with four other boys. They both go to concerts and record signings together and hang out all the time.
Kimi and Angelica aren't super close but are still friends. The two go to the mall together along with Lil & Susie. They both are fans of The Sulky Boys & Emica.
Kimi and Dil don't interact with each other too much in either of the two series, but they are good friends & Dil did really want to and tried to help the guys when they tried to renovate Kimi's room after thinking her room was making her depressed (it didn't).
Susie and Kimi are very close friends. They always talk, have each others backs, like the same stuff, join the same clubs (unless it's cultural), and attend each others events.
Kiki is Kimi's younger sister and she’s the only sibling related by blood, through her father. Kimi was jealous of Kiki when she thought their dad liked the new baby better but when her dad brought Kiki over to the Finsters house so she could meet Kiki she was ecstatic and so excited to hold her. During that visit Hiro also announced that he had enlisted Kira and Chas to help him find a house nearby so he could see Kimi more regularly and so Kiki could grow up with Kimi in her life.