Uther can be summoned in three classes and possessed a different mentality for each. The Caster is the 'Wise King' talented with Druid Magecraft, the Berserker is the Half-Dead King filled with nothing but pure anger and rage towards the world that stripped him of everything. This Saber class is him as the young Proud-High Knight-King.
This is Uther when his spirit was strongest when he had bested Vortigern taken the throne in his early 20's, probably even late teens. He is big-hearted, energetic and full of hope. Although he has a tendency to jump the gun at times, he is a truly righteous figure. He has pride in his strength but even more in his friends - particularly his best friend Merlin. He is not yet used to being called a 'King' but he will do his best to help people and take advice of others as in his eyes that is what a king should do.
Incidentally his memories of his later life are blurry and he cannot recall them well. He retains an embarrassing crush on Igraine though he will easily move on if prompted to as it has not yet developed into the obsession he would possess in the Berserker class, he also doesn't remember what he did to win her love.
Also, he is where Arturia got her appetite from. He can easily gorge himself on huge feasts, but really appreciates small and flavourful dishes. Summoned into the modern day, you could easily find him spending all his masters money at a sushi bar. His favourite dish is Beef Teriyaki.
Bond Lines:
Lvl. 1: I fight to save my land and my children, the responsibility is heavy but I guess I can take it.
Lvl. 2: A white cloak? Oh yeah, Lily servants tend to wear white don't they? I'll be honest, it got really messy really quickly. I tried to wash out the stains. I preferred red to be honest. Merlin is fond of his jokes but if you calm down and actually get to know him, he's a pretty swell guy. Won't clean for his king though…
Lvl. 3: I don't really remember much of my later life to be honest. Not much after uniting the kingdom and meeting Igraine. She was so cute… I don't even remember my children or what I did to meet that lovely lady.
Lvl. 4: I was a bad king, wasn't I? I don't remember but I've done the reading. I screwed everything up entirely and left it for the next generation to clean up my mess.
Lvl. 5: … Do you have any advice to be a better king?
Relationships:
Merlin: Saber's mentor and best friend. Acting differently than his daughter, the relationship these two share would be closer to what people in the modern day consider to be Bro's. Incidentally if summoned in a war together - you will see the most complex and bizarre series of 'high-fives' ever. They go drinking, laughing, talk about girls, play video games together and forget they're supposed to kill each other. If summoned together in the events of Grand Order, they would take advantage of this and spend a lot of time goofing off together. They may try chatting up some of the female servants, but frankly Saber is an
awful wingman.
Arturia: Saber remembers he had at least one daughter and remembers he had a child who was Arturia. However he remembers nothing else about her at all. He has nothing but the upmost respect for Arturia and is proud of his child in suppasing him in every way. However he is ashamed he doesn’t remember a single thing about her is frankly to embarrassed to speak to her. He may be caught occasionally mumbling
"I certainly hope I was a good dad." He also doesn’t seem to remember Morgana. Like at all. This will not go well for him.
Uther Pendragon Caster Alter: The person Saber despises most, his future corrupted self. He represents all his failures, screw ups and shortcomings all wrapped up in a neat bow.