Who can explain the relationship between Wu Qilong and Su Youpeng?

What kind of relationship? They are very close friends and confidants. When Wu Qilong sang "Bon voyage to you" in a program, Su Youpeng came out from behind. Wu Qilong was moved to tears by this feeling. . .

Similarly Su Youpeng participated in the show as a guest. Wu Qilong was injured and was invited to go. He agreed without saying a word!