After Faking My Death as an Undercover Agent in the Immortal Sect

The blurb and title may change before the story begins, but the premise will stay the same.

Fake death / amnesia / pregnancy / imprisonment / widower raising a child alone / younger brother's husband and his older brother (fake)

Ji Xuanqing is the lord of the Demon Realm, while his lover is an undercover agent sent by the Immortal Sect. The day he found out, Ji Huaiying was giving birth. He thought that as long as he pretended not to know, they could still live together in harmony, just as before.

It wasn't until he saw Ji Huaiying feed poison to their newborn that he realized just how much Ji Huaiying hated him. He didn't even want to keep the baby who carried half his blood.

Ji Xuanqing severed Ji Huaiying's meridians, broke every bone in his body, and imprisoned him in a flooded dungeon.

He hated Ji Huaiying for deceiving him, and hated him even more for not loving him.

Later, Ji Huaiying really did die. Ji Xuanqing kept vigil for eighty-one days, but Ji Huaiying never woke up.

Three hundred years later, he met someone named Duan Huaixu, whose face was almost exactly like Ji Huaiying's.

The man said he was Huaiying's older brother and had come to avenge him. He would make Ji Xuanqing pay for every last thing Huaiying had suffered, taking it all out on himself.

Gentle yet ruthless city lord x aloof swordsman with amnesia

Duan Huaixu and his younger brother Ji Huaiying are the same person. Duan Huaixu is an identity Ji Huaiying adopted after faking his death and losing his memories. They're called brothers, but are really one person.

A delightfully melodramatic story, with each of them giving birth to the other's child.

Theme: Perseverance