Always An Angel Never A God

In which the twin sister of Sirius Orion Black always puts her brothers first, at school and at home, without realising what issues this will bring her before it is too late. Does she stay to protect them even after they are gone or does she give herself a fair chance at survival?
Even with all the worries in the world she never asks for help. She thinks it makes her feel weak. She shuts off sometimes when the stress is too much. She can't help it. She knows the stress will kill her but she can't trust anyone.

or

Twin sister of Sirius (older by 12 mins) is always an issue in her family, but once he leaves she can no longer fight against it so she gives in until she has enough strength to fight.