Gone girl |Sirius Black|

Ever since River and James started 2nd year at Hogwarts her brother left her out of everything. Games, pranks, etc. She had no choice but to make her own friends and leave her brother behind. That was until 3rd year. Her parents stopped paying attention to her completely and only focused on James. She got sick of this and left without a trace. Nobody saw her for over a year. Until the beginning of 5th year. She shows up out of the blue. Although nobody seems to know her at first James does and so does Sirius. A lot has happened in that year and no one can find out. But of course Sirius Black can't keep himself out of other's business and ends up finding out River's secret. What will he do? Will he tell the rest of the marauders? Or will he keep it to himself?