The Coast Of The Waves summary:

My only brother in this world, Haewon, is not only my family but also my sole protector. Yun-oh has been secretly in love with Haewon for a long time. Being a beta, Yun-oh believes that a relationship is impossible since Haewon is an alpha. Despite this, Yun-oh hides his feelings and stays by Haewon's side. However, Yun-oh unexpectedly gets caught up in Haewon's rut, revealing the feelings he desperately tried to conceal.