Hithaerion & Halvion's Links
Both twins were taken in by Ninimiel when she visited The Last Homely House and discovered that the twins were left behind by their parents, who heard the call of the sea after a battle with orcs left their father thoroughly injured and traumatized, and their mother unable to part from his side even for the sake of their children. They warmed up to Ninimiel quickly when she visited, and eventually Elrond gave them leave to return home with her and her twin.
Ninimiel saw herself and her brother in the boys when she met them, espeically considering their parents had also left to the seas and beynd. Her attachment was near instant, and Elrond could see and uderstand the situation. He allowed her to take the boys, trusting in her ability to raise them. She is wholly unbothered by their pranks and games, and they are a light in her otherwise rather simple life where she lives.