There are a few things I think are important.
1. When you are engaged in 1 vs 1 situation, you should have decent chance to win the fight no matter what role you play.
2. Your character/hero asset should allow you so that you can perform according to your skills, maximum potential.
3. You should feel the weight you bring to the battle. You are important. You are the protagonist of the battle.
4. Ultimate abilities are unfair and it hurts the nature of brawl game. Normal abilities should be strong enough to be considered enough "pieces on the board". Instead of "ultimate" perhaps add one strong ability that has longer cooldown.
Overwatch's Zarya has an ability that can protect an ally and cleanse bad effects from a target.
Also she gains bonus to her damage whenever she successfully blocks incoming damage.
I think this is an excellent skill/mechanic that fits the support role.
Also she can bring dead allies to alive. This is a powerful move but really playing Mercy feels good. But this is such a strong ability I think it requires a way to tone down; like limit to one person and one person only.
So at the end of the day I came up with new support that plays somewhat like Mercy/Zarya.
An image I found on internet. Flame princess from adventure time.
A support character that heals with her beam from her light source. The light source gains more heal/damage if she can absorb incoming damage. She can also revive people after channeling for a few seconds(has 30 seconds cooldown) .
She sounds very strong and I like her to be center of balance; I want that kinds of power level for each and every hero.
And yes she can fly into an ally too.
Her left click is that of Symmetra, automatic tracking beam, right click is that of Zarya's left click, straight forward beam.
Left attack is used as a heal and right as damage method. And as you might expect left click doesn't require much aim, while her right click does so intensively.
And below I ramble her lore that I have in my mind.
Born within the center of universe at the very beginning of time, her race is made out of massive pure energy that is the fiber of very existence itself. As the only heir of one and only fire kingdom she is bestowed upon a duty to guard and watch over existences, whether good or evil, that are born from this universe.
Though OW is a great game in terms of visual it has its flaws.
Reflecting environment had always been a challenge to graphic programming and OW tries to overcome this task by assigning "reflective map" fore each area rather than computing it.
Which is good enough for the most parts. But instead of doing that, I am doing Forward + or sometimes called tiled deferred rendering.
This should give the game more coherent look.