This is JazzyLegend 's OC, Duskflame

Name: Duskflame
That's a pretty neat name, and the prefix dusk- isn't all that common, but the suffix flame- is, but it's a good name.

Looks: black and ginger tom with yellow eyes, broad shoulders, scarred muzzle, chest and flank, and white underbelly
He seems like a strong and well-built warrior.

Personality: Defensive, quiet, and calm. But can be passive, aggressive, but he will serve his Clan until the day he dies.
I like how you added flaws, but he kinda needs a few better traits, don't you think? He could be protective, loyal, brave, courageous, something along those lines.

Gender: tom
We finally got a tom!

Backstory: He's always been a cat of few words, except for when his sisters picked on him in their nursery days. As an apprentice, his mentor was attacked and killed by a fox, the leader then took him as his apprentice. The leader was rather cruel to him as he trained him, causing Duskpaw to hate him. After his warrior ceremony, he is immediately assigned one if his sister's kits as an apprentice upon her wishes. The apprentice was named Pinepaw (later Pineash). After a few moons of training Pinepaw, Duskflame starts unintentionally snapping at him, chasing the apprentice into the medicine cat's den. It isn't until his other sister's litter when he got an apprentice. This one was named Emberpaw, later Emberwing. The stubborn she-cat stays with him until her warrior ceremony. He proves his loyalty and gains the rank of being deputy after the current deputy, Thornbranch, is killed in battle with Thunderclan. He protected the leader from a warrior trying to attack him, sustaining deep injuries in the process. After the battle, the leader decides to make Duskflame deputy.
Not too tragic, which is a good thing. Not all backstories have to be sad.

Other: He has a crush on Trushwhisper, a ThunderClan tom.
Never heard of a gay cat, but I guess you learn something every day. Points for originality here!

Cause of death: none
Just remember, he can't live forever.

Mate: none
That's fine.

Kits: none
That's fine as well.

Clan: RiverClan
RiverClan is good, and I think Duskflame fits right in!

Rank: deputy
Yes, he seems like deputy-material.

Afterlife: none
Most likely StarClan, though.

Overall rating: 9.9/10
Duskflame is a very well-developed character! I love him! Just add some more positive things to his personality, but change nothing else! He's great!