There's been a running theme with gold = blessed and red = aggressive in Elden Ring. Gold eye enemies drop more runes, red eye enemies aggro and from increased range. Orden is golden light and almost every major faction opposing the order in the game are shrouded in red(volcano manor, three fingers/madness, Mohg/cult of blood. Marika is golden, Radagon is red, etc. There's an antithetical theme they've been running with.
Considering who their parents were, I always assumed Malenia and Miquella were the extension of Marika's duality - her benevolence in him; her violence in her. But it wouldn't surprise me if Miquella due to Mohg's experimentation ends up a fully realized person and becomes Messmer - Miquella tainted by bloodflame. Arm length and general shape line up with the arm out the egg as well.
...
Give me golden-haired Valkyrie Malenia as summonable help for the fight FromSoft.
Do it you cowards.