Asgore

Asgore is a secondary character who made his first debute in Prologue: Broken and Bruised. He is the king of monsterkind and the ex-husband of Toriel, the former queen of monsters. He is the father of Asriel and adoptive father of both Chara and Rose.

Appearance
Asgore is tall in length and is usually seen wearing a large purple cape, which underneath, he wears golden armor. Unlike the other monsters, he doesn't wear any shoes.

Personality
Asgore is a kind, softie monster who absolutely hates having to kill the humans that come down into the Underground. He has an interesting "obsession" with tea. Asgore is not a person who actually wants to cause havoc to humanity.

Prologue: Broken and Bruised
Asgore is first mentioned at the beginning of this chapter, where Toriel yells for him to get a medkit to treat Rose's wounds, since she was losing a lot of blood, and really fast. However, they fail to save her and gave her a proper burial. A decade afterward, Asgore has a baby with Toriel and named him Asriel. Soon after he is born, Rose also becomes apart of the family, and they live happily together as a family. One day, Chara falls into the Underground, and also becomes an adoptive child of the Dreemurrs. 2 years after Chara's fall, Chara and Asriel are found dead in front of the barrier. Struck with grief, Asgore declares war on humanity as Rose and Toriel retreat to the Ruins for the next 29 years.

Chapter 2: The First Reset
Asgore does not technically appear physically in this chapter, however, he does call Rose. It's mostly talk of how the human is doing and so on so forth, however, a funny thing that happened was when Rose asked him how he got her number, he stated that "You never changed it" and she noted to change her phone number immediately after hearing that.

Toriel
Toriel is Asgore's ex-wife and they haven't seen each other in 29 years. He misses Toriel a lot.

Asriel
Asriel is Asgore's son, and after he died Asgore was struck with grief and anger and declared war on humanity. Simply put, Asriel's death was a push factor in the declaration of war on humanity.

Rose Elizabeth Violet
Rose is Asgore's adoptive daughter, however after Chara and Asriel died, they started drifting apart, although Asgore does miss her.

Chara
Chara is Asgore's other adoptive daughter (however, Chara is referred to as they so technically, they're his adoptive child) and before they died they and Asgore were really close.

Undyne
Undyne and Asgore have not been seen interacting much, however, in the Undertale True Pacifist route, Undyne and Asgore seemed to sorta treat each other like father-daughter, although Undyne is not actually Asgore's daughter.

Trivia

 * Despite him trying to make amends with Rose, she never accepts any apologies, nor even listens to him when he tries to explain why he killed the human children, and that he never killed her sister.