AU-ish. Avery Hotchner is Aaron Hotchner's 18 year old genius niece. When her parents (Hotch's brother and sister in law) are killed, Avery decides to leave college and take Hotch's long-standing offer to be a part of the BAU. Taking the job means gaining new family members- the rest of the team. Slowly, Avery learns to trust and love again - and she might even perhaps fall in love with the team's very own Spencer Reid, the resident 23-year-old boy wonder.
(yes I realize Spencer wouldn't be 23 in this, as it is loosely based around season five, although hardly anything from the actual show applies, besides the lives of the characters. Emily Prentiss is in this, and no I do not plan on "killing" her or having her leave. Like I said, loosely.)
Disclaimer: All characters belong to Criminal Minds save Avery Hotchner.