Godric Gryffindor was in all things, a teacher second. So when Rowena approached him about a school, he was all for it, especially as it would give him a chance to showcase his skills. Revolutionizing how magic is passed on wasn't as exciting though, so he encouraged his students to make it interesting. Soon enough, there was clear favoritism for those who'd push the rules, and play more than learn. Rowena disapproved, Salazar scoffed, and Helga laughed.
Rowena Ravenclaw was in all things, a teacher second. She frowned at the mistakes made by parents, magical knowledge passed down, but only selectively for what the parents were good at. She feared that soon, magic would die out, and the world would forget. She was a scholar first; the idea that knowledge would disappear, unrecorded, forgotten and in the past, scared her more than the fight she'd take up to build her school. Her research consumed her. She never noticed the cracks in Hogwarts' foundation until Helga dragged her to a window to watch Salazar walk away.
Helga Hufflepuff was in all things, a teacher second. An orphan, and shunned by her family because she made things happen. A secret she managed to keep. Up until her brother fell down from a tree and she flung a hand up; he didn't crash. She'd expected gratitude (it was a good thing- saving lives). Her family frowned collectively and in the night, they handed her some bread and water and made her swear to never come back. Rowena found her and taught her. Her first magical word was muggle. So when the school opened, she made a point of treating everyone the same, even though she knew that experience was a better teacher than she was.
Salazar Slytherin was in all things, a teacher second. When Godric asked him to help him out on his newest endeavor, he thought it was only right he help him (someone had to keep Godric in check after all). It helped that Rowena's smile when she challenged him on charms theory warmed the coldest parts of him. He narrowed his eyes and mumbled 'muggle' when she introduced him to Helga. He didn't force a smile, he wasn't polite; his mind was occupied with the memories of his sister being consumed by flames, and he a small five year old boy, powerless and screaming his lungs out. He'd never forgotten the smell of burnt flesh.