Thomas

Thomas is a boy that Lucy likes, but he regularly ignores her to think of her sister's friend Valerie who babysits for him.

Thomas' friend is briefly shown once.

His name isn't revealed until much later (pg 26 of season 2) prior to that he was only ever referred to as the "neighbor kid".

Chloe is surprised by his innocence. Val later gives him pointers on how to interact with girls, which benefits his interactions with Lucy.

On page 100 Val mentions "Thomas' parents" plurally to Chloe in a phone conversation, indication he lives with more than one.

Tom is a nickname first used for him on page 31 of season 3, by Chloe.

He and Mary are invited over on page 118/125 of ch 3.

Thomas later mentions to Val's brother Mike about being with four people. Only three are known: Lucy, Mary and Val. It's not clear if by the fourth he meant Chloe since he and Chloe teamed up against Lucy once but did not interact directly.