Ruby Red by Kerstin Gier

1st in Ruby Red series.  Sequel is Sapphire Blue.  First published in Germany.

Gwen is 16 and lives with her mum, siblings, grandmother, aunt and cousin in an upperclass London neighborhood.  Her extended family doesn't pay much attention to her, focused on her cousin, believed to be the carrier of the time-travel gene that runs through her family and sure to show up very soon in the form of an abrupt trip to somewhere in the past.  But all is not as it seems.  Since a mathematical formula had worked out that Gwen's real birth  date was the birth date of the next time traveler, and her cousin was also born that day, Gwen's mum and (late) father secretly falsified her records to indicate Gwen was born the day before, allegedly in the hopes that she would be able to live a normal life (and since she was born at home with a midwife, no one was the wiser.

Will Grayson, Will Grayson

Told from alternating POV's, this story focuses on a few months in the lives of two teens with the same name who meet through change and whose lives intersect at the large point of Tiny Cooper, the best friend of one Will and the new boyfriend of the other Will. Themes include looking at what makes people friends, dealing with romantic interest, how people can be very different but still love each other, a bit about telling friends and family that you are gay and a bit about depression and mental illness in teens. Funny, witty, relationships told from a guy's point of view, matter of fact about homosexuality. Lots of IM and texts quoted.

SLJ grades 9 and up