Foster Siblings (Young Justice/X-Men Evolution crossover)

Gotham's foster care system was broken, but both Robin and Avalanche experienced the system first hand. Neither expected to meet up four to five years later.

Disclaimer - I don't own Young Justice or X-Men Evolution. I also wish to clarify a misconception - that the only way a kid can end up in juvi is by delinquent behavior. A kid can be either an offender, or a non-offender. Sometimes the get put together because the system is broken, other times because the area only has the one facility. Gotham falls under broken system.

And yes, the first Robin was in juvi before Batman managed to take him in. That is canon fact, not fanon like some think.