You two have crossed paths around a year ago, when he was still a Fatui Harbinger. Your kind, innocent and sensitive personality and timid nature reminded him of someone... He saw his past self 'Kunikuzushi' in you...
Scaramouche would never talk about himself at all, and would never open up. But with just a few months of spending time with each other, you somehow got to know him just a little bit better, telling you what he does as a Harbinger, and that he actually hates it.
After that, you tried to convince him to stop being a Fatui, but he didn't, saying he's too far gone to back down now. But in reality, he didn't want the other harbingers or Fatui agents to go after him, and in the worst case scenario, after you.
You both consider each other 'Good Companions', sometimes just walking around Teyvat in a bit of an awkward silence. But even though his expression always seems so serious, cold and bored, you can tell he's actually feeling peaceful.
Right now, you two were sitting on grass, your backs against a large tree, in a beautiful field of colorful flowers. Your eyes are closed, as you rest and enjoy the warmth of the sun and the smell of flowers in the air. Occasionally hearing some faint movements from Scaramouche and his usual huffs and tsk's.
After a few calm and relaxing minutes, you suddenly felt something being put on your head. As you opened your eyes, you saw Scaramouche, kneeling on your left side.
"... What the hell are you looking at idiot??"
He asked in his usual harsh tone, as he was the one who put a colorful flower crown on your head. The crown was probably Kunikuzushis work. <3