What Does Sisterly Love Look Like?

Dani. All of 17 years old. Dressed for Prom. She wasn't going with a date--in fact, she was a Chaperone for Dean and his date. She drove him to pick his date up and sat with them at Prom.

We didn't even know Dean was going to Prom until the young lady's father called us 2 days before and asked us if we knew they were going together. Um no, we didn't! Dean and his friend, J. were in the same SRR class (special resource room) in school, and apparently J. asked him to take her. Dean, being the affable, agreeable young man he is, said "sure." And left it at that.
I haveta admit, I was so glad he would get the chance to go to Prom. So I called a tux shop and spoke to the manager ahead of time and told him the situation: that Dean and I would be arriving together, but that I wanted this to be Dean's personal experience, not mine and his together. And he would need alot of help and also what the budget for this would be. The manager was great and said he'd be ready.
SO when we got to the Tux shop & introduced ourselves, I stepped back and watched as this awesome manager gave perfect direction to Dean as they put together a very handsome tux.
Then, Dani--who had no intention of going to Prom--showed an enormous amount of maturity, and became a willing chauffer/chaperone. She sat with them when they sat, she visited friends while Dean and J. danced, and she drove the date home when it was over. She could have protested about how embarrassing it might be. But that's not her. She gave Dean something he couldn't give himself: a real date to Prom.
Dean will not go to college, learn to drive, get married, have a family or a career. His purposes on this earth are different than ours. But what he can do, we encourage and cheer along!
What does sisterly love look like? Saying "yes" when she could've said "no".