Fate/Grand Order

In Celtic mythology and the Ulster Cycle, there is a great hero who stands above all.
A "Child of Light" born of the blood of the Sun God, Lugh.
Also known as the Guard-Dog, he seems to be the same individual as the Lancer that is summoned with the same True Name.
However, his body and mental age seem to be a bit younger than "the other one."

Height/Weight: 184cm, 71kg
Origin: Celtic Mythology
Region: Europe
Alignment: Lawful-Balanced
Sub-Attribute: Heaven
Gender: Male
Can use Rune spells just like "the other one."

He's a wild but cool kind of guy.
Even though he won't judge between justice or evil and decide which one is better, he cares deeply about being just in the world.
But he isn't mature enough to accept the many unfairnesses that occur in the world.
He's a creature tamer, and has a great affinity for dogs.

Compared to the Lancer summoned with the same True Name, he wears heavy armor.
Despite this, his dexterity parameter is A+, surpassing "the other one."
It's not that he's more capable, but that he's younger, and overenthusiastic which causes several differences between them.

『Gáe Bolg』
Rank: B/B+
NP Type: Anti-Personnel/Army
The Spear which Reverses Causality.
The scarlet spear and related arts which he
received from his mentor, Scáthach.
Capable of Anti-Personnel Thrusts and Anti-Army Throws.

Compared to the other Lancer, he has a bit more affection for his teacher, Scáthach.
It's unknown whether this is due to his age or how much time has passed.
It's true he cannot accept the unfairness of the world, and the fact that it's all shades of gray, but...

He probably thinks it's commendable that his Master is attempting to correct human history, and most likely wouldn't mind lending a hand.
However, you must be careful, as he may not respond the same as the Lancer with the same True Name.