Fics like back when we were card sharks (playing games)

The BAU have a new case - a string of suspicious suicides in Las Vegas with too many similarities to be coincidental. As they start to unravel the mystery, Derek becomes increasingly preoccupied by one of their key witnesses Spencer Reid, a chronic gambler and drug addict who never left to join the BAU. When it becomes obvious that there is a serial killer at work, the team utilises Spencer's intelligence to help crack the case. Derek, however, can't help but feel protective over the younger man, especially when the case takes a dangerous turn. Spencer doesn't want his protection. He's lived his whole life fending for himself and barely just surviving. And yet, he finds that maybe he doesn't mind the fact that someone other than himself cares about his wellbeing. Maybe, just maybe, the two of them will find their way to each other. Or; A universe where Spencer never joins the BAU, but crosses paths with them anyway.