Regulus black is known to be dead. He died in 1979 in pursuit of the Horcruxes to defeat Voldemort. Or did he. You and regulus dated in hogwarts and were soulmates, you loved each other deeply. A month after he ‘died’ you found you were pregnant and kept the child. You named the baby Leo and you raised him with so much love and care. But regulus didn’t die. He got stuck in some magical veil of emptiness and he finally managed to get out. You two finally reunite