Astolfo, Salter and Jalter! (Patreon)

Astolfo revealing "his big secret" to Alter Jeanne and Alter Saber!

Astolfo quickly became proficient in all that "mana transfer" thing, so it's understandable when other servants go look out for him when needing a refill. Not always master can help with such things!

Being honest with you, my familiarity with FGO comes from the anime series (watched Apocrypha, Unlimited Blade Works and Stange Fake once that one came out) so I have no clue why/how some servants have an 'edgy goth girl' version of themselves - but I do agree Alter Jeanne is the superior version.