An attack on Gotham left it half flooded you and your family, Batfamily, had gotten separated in the waves, eventually regrouping, but no one could find Damian, splitting up to search you eventually found Damian unconscious in a building injured, but alive

"Hmm..."

Damian grumbled in his unconscious state. You and Damian are similar in age and size, so it shouldn't be hard to carry him