Does Erwin Smith Care?
Nile Dok - Erwin and Nile were in the same Training Corps and had intended to join the Survey Corps together, but parted ways when Nile fell in love with Marie and chose to join the Military Police instead. Their relationship was strained, though Erwin trusted Nile enough to give him a warning before the coup.
Keith Shadis - Erwin respected his fellow soldier and former commander, Keith, despite the many losses that were sustained under his command. Keith shared this respect and after resigning his post, would personally select Erwin to be his successor as Commander in the Survey Corps.
Levi Ackerman - The two had a mutual trust and respect for each other's skills. He willingly followed Erwin's command, though that did not keep him from speaking his mind.
Hange Zoë - Erwin greatly valued Hange's intellect, and when he felt he was nearing death, he made sure Hange knew they were next in line.
Mike Zacharias - Erwin and Mike had a deep mutual trust due to their lengthy time in service together, as well as respect for one another's skills as soldiers. Most of the time he was Erwin's right-hand man, and loyally followed his every command; despite their closeness and long time together, Mike still found Erwin difficult to read.
Armin Arlert - Erwin seemed to recognize Armin's potential as a strategist and had started entrusting him with commanding roles and making decisions in the Survey Corps. When Armin learns Erwin had to die so he could live, Armin was shocked at the revelation.Years later Armin regrets being saved instead of Erwin as he claims he would be able to handle the situation the Survey Corps was in, highlighting how much respect and value Armin saw in Erwin.