Even though this is quite short, its a very good poem. I got goosebumps reading it, and i almost never get goosebumps. i also like the style of the poem, I can never write couplets, so very good on that!!!
"A faint glint of hope, resting in his eye
Maybe his sister didn't mean to die"
"Maybe just maybe, she wanted to live
Just for her life back, anything he'd give"
^^ You used the world "Maybe" too often here, so it became a little bit annoying. Instead of using the line 'Maybe his sister didn't mean to die', you could use a question: "Did his sister really mean to die?"
"To see her alive, not dead in her blood
He'd fly to heaven, like good brothers should"
^^ That second line, "He'd fly to heaven, like good brothers should" was truly beautiful.
"He couldn't cope, without her by his side
So just to see her, a hero he died"
^^ I wasn't sure whether to call the ending beautiful or extremely heartbreaking. It's certainly a beautiful *and* extremely heartbreaking poem though.