The flashback to Asura and Durga after Mithra is born, it shows that before all the shit went down, he had a really happy life, for christ's sake he rocks her around, and he's freaked out when she cries like any new father would, it's just sweet.
Episode 22 has him admit his worries; unsure what to do whenever Mithra cries, and asserts the best he could do for her is punch anyone that upsets her otherwise. Durga, both amused and touched, assures him she would raise Mithra while he focuses his attention on protecting the world for her. Oh, and apparently Baby Mithra cries whenever Asura leaves the house. All together people. Awwwwwwwww.
Another flashback in the episode 20 interlude shows us a cute little scene of a dinner in the Asura home, apparently Asura has eaten Mithra's vegetables because she didn't want them, and Durga is reprimanding him for it, while Mithra just sticks out her tongue during the whole scene, obviously amused. The whole scene just feels so...real. Doubles as a Tear Jerker because Mithra is having this flashback while in Chakravartin's clutches.
After Emperor Strada was murdered and Asura killed, the Seven Deities made Asura out to be an insane, depraved monster who murdered Strada, and that it was only by the heroic efforts of the Seven Deities that he was defeated. However, after Asura dies a second time, the villagers who reside in the area around where he is sealed believe that he is watching over them, as there are fewer Gohma attacks in that area. Even though the Seven Deities have made Asura out to be a villain of the worst sort, these people believe that Asura has been protecting them for those centuries when he was sealed away in stone. Considering what kindofperson Asura is, that may hold some truth, if only because the Gohma are afraid of making him angry enough that he comes back to life again.
From what has been translated so far the song is a real Tear Jerker.
A Heartwarming In Hindsight example: While Asura was in his blackened Wrath form, he was relentless towards anyone Shinkoku or Gohma related. However, according to a Shinkoku soldier watching from the sidelines, he left the civilian demigods and humans alone. It takes a special kind of heart to understand who is an enemy or not, especially when at this point he is so blind with rage he can't stop fighting.
When he went Wrath form during the first few battles with Chakravartin, Asura was still sane enough to know where he was and why he was fighting the entire time.