(This is the second season one btw, a bit of spoiler alert, so...)
While you, Yuichiro, Shinoa, Yoichi, Shiho, and Mitsuba were on your way to Guren ichiose who was fighting the noble vampire named Ferid Bathory, Crowley Eusford, Lacus Walt, and Renē Sēmm all alone with his team.
As the five of you made your way to go there, and when you both finally arrived, Yuichiro or you called him Yuu, he froze in place when he saw his childhood or he called him Family which he referred to Mikael who was on Vampire side, he didn't say a word while you and your team fight with the low and noble vampire, barely even scratching them. Mikael (whose only Yuu Family he considered) tried to pursue him to just leave you and his friends behind, calling you and his friends "brainwashing" Yuu. But of course, he didn't trust that since the four of you were the only friends he couldn't bear to lose again. He fought with his family, Mikael. But he stopped before he killed him, and Guren was mad at this since he's heavily injured and couldn't fight a lot longer anymore.
Guren: "finish him you idiot! It doesn't matter anymore if he's your family! He will kill us if you haven't finished him off!" Guren said as he held his left waist that was injured, but, out of cruelty, Ferid Bathory just kicked him off to the wall to shut him off. With a cheeky smirk, he spoke.
Ferid: "aww, c'mon. What's wrong? Can't fight anymore? Where's the always-so-cocky you? Did you lose it? Or... Perhaps it's because you were injured?"
Back on you and Yuu teams, you, Shinoa, Yoichi, Shiho, and Mitsuba, were struggling to keep up and fight with the noble vampire. Yuu's mind was in a mess, Mika kept pursuing him. You, Shinoa, Yoichi, Shiho, and Mitsuba are trying to get Yuu and Mika away from here so they can talk. Big mistake, you let your guards down... And the noble vampire saw this chance, didn't hesitate. They each lounge at you, Shinoa, Mitsuba, Yoichi, and Shiho. They got pinned on the ground, disarmed, and couldn't move due to the difference between their strength. Their names are Crowley Eusford, Lacus Welt, and René Simm. And Ferid specifically entangled you, looking back at Yuu whose face already darkened.
Yuu: ".... No... No... No.... Please... Don't..."
Shinoa: "g- get off of me..." She tries to struggle but is useless
Mitsuba: "r- run damn it Yuu!"
Yoichi: "y- yeah... R- run... L- leave us Yuichiro-kun..."
Shiho: "damn you... Go run you idiot!"
But he didn't run, seeing his friends being held by a dirty noble vampire, made his blood boil. And... They didn't stop... As if it wasn't enough for the vampire, they bit you and his friend's neck... Boiling his anger even more.... His friends, screams, and Ferid...
Ferid: *"don't worry, I'll be gentle~" he then bit your neck, fueling his anger more.
Yuu couldn't take it anymore... He had to do something about it.... But it's only a matter of time his true self would take over his body and lose control....