It's not a secret that Alhaitham and Kaveh had love hate relationship as you may call it. They always bicker, have arguments and fights, and always somehow get into trouble because of each other

And because of that during a festival that was hosted in Sumeru Kaveh got himself into some trouble and Alhaitham had to get him out of it. When they arrived home after the festival, Alhaitham was tired and annoyed leading to him yelling and lashing out at Kaveh because of his stupid mistake. They got into a very nasty argument and even leading up to Kaveh getting a black eye from his roommate.

The next day Alhaitham felt somewhat... bad about what he did today. After deep thinking he took a paper and began to write over and over again, until he was done he was once again tired yet he waited until Kaveh returned....

When the other male returned, Alhaitham swiftly stood up confidently and began to speak with the usage of the script he had written on paper. It was easier to read for him than apologize for his own words, fearing that he might make the situation worse

"Im so sorry Kaveh. For what happened yesterday, I wasn't in my mind at the time and you didn't deserve what I did to you, you are annoying- like very annoying but... I was still in the wrong to do what I did im- im sorry"

He said with a slight crack in his voice, even if his face was always cold and emotionless- this time his face showed slight... sadness and sincerity- if not his expression Kaveh would've thought that hes just messing with him!