How to write a character response?

So I am reading a novel called le morte d'arthur and I have to write a response to someone's early life. His name is sir Tristram and in his early life this is what takes place:

-his father is captured and held captive by someone who loves him(his father is a king)

-when this happened, his wife (the queen) is in grief and is pregnant with his baby, she runs into the forest and gives birth to Tristram.

-tristrams father (the king) remarries

-the women he marries tries to poison Tristram because she is jealous of his inheritance.

-to poison Tristram, she leaves a bottle on the table and expects Tristram to drink it, but instead her son does.

-after the king finds out about how his son was almost killed by his second wife, he tells. The people to kill her.

-sir Tristram (the one who almost got poisoned and died) tells them he doesn't want her dead even though she tried to kill him (because he is a nice person)

So the problem is I don't know how to write a response (300-500 words) the last time I wrote a response It was just a basic retell of the story.

I know I am supposed to incorporate my own ideas because it is a response but it is really confusing me, I need advice or an example of a sample character response to the life of someone.

Thanks so much