I was really confused, because I thought "last" meant "previous" not "this most recent." But after thinking about how the first seme was really cute and...normal, I guess (as in, not immediately being attracted to the MC), I definitely agree with you.
This most recent seme, I found him quite frightening as well. He entered the MC's life too quickly, without any trust or mutual love to develop between them, which would result in 'emotional hurricanes' of jealousy/misunderstanding, and, quite honestly, this causes the poor MC a lot of stress. He has to worry about his appearance, since the seme keeps calling his name in the office in a familiar tone. The seme also barged in and made himself welcome by, first, fucking him and then living in his home. This sudden, impulsive action is probably from meeting him on the subway and falling in love at first sight, but, if so, he should confess his love first and gently ease his way into the MC's life to get his trust and love.
This seme from the last story...
Idk, I find him scary.
People who are way too gentle and literally enter your life that fast have the potential to be like emotional hurricanes, you know, too intense, too fast, ends leaving tons of disaster behind...