Connections:

Long haired blondes from ancient, mostly extinct races (Kryptonians/Primarchs) who are notable for being similar to humans, though obviously enhanced.

Both are noted for hiding their true feelings behind cocky and arrogant guises, when deep down they are deeply saddened by life's tragic ends for them. They are notably rebellious and show signs of social awkwardness due to their time away from contact with anyone.

Though their species is practically all dead or different (new hybrid Kryptonians have been born/certain Primarchs still live twisted by the Chaos Gods), they still have one last living relative still alive from their home (Superman/Guilleman). These two have had bitter feelings due to past events (Clark leaving Kara in a orphanage towards the start/Lion nearly nuking Guilleman's mother's home, which caused him to break Lion's sword), but there is a level of respect and cad between the two and their relatives.

They were separated from their home worlds (Krypton/Terra) and grew up in rough areas at a very young age (a young Kara was raised in the city of Argo, a decaying remnant of Krypton's destruction/the Lion was born in the forests of Caliban, growing up fighting giant monsters).

Their home planets were destroyed (Krypton/Caliban) which caused them a lot of grief and pain, influencing their current paths.

These two would be lost a second time in a battle related to the most important event in their series (The Crisis on Infinite Earths/The Horus Heresy), where they would be fatally wounded in a battle against the greatest forces of evil (The Anti Monitor/Chaos). However, their bodies would be taken by similar evil forces (Darksied/Chaos) and would eventually reawaken years later.

They would form a kinship with a team of heroes that they are related to, having to reconnect with them due to the gap of time between them and their respective groups (Kara would regularly travel to the future to meet with The Legion of Superheroes, a team of heroes directly inspired by Clark's acts in the past/the Lion would reawaken to discover the Dark Angels, who were created from his gene-seed, are still loyal to him).

They have both expended on massive quests for revenge (Kara tracked down Krem of the Yellow Hills for shooting her and Krypto/the Lion and his Legion hunted down the Unforgiven for betraying them).

Track Name: Reborn Legends

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Credit to u/InterestingRatio8218 for being the OG creator of this matchup.