"This is strange. Very strange."
Usagi did not like the looks of this. After emerging on the other end of the portal, he had expected to find himself in the foyer of Yume's castle, standing before Yume herself. Instead, he and Donatello were in a bare, dark room set in dusty stone. A dirty window above them allowed some amount of moonlight to enter, but they were otherwise mostly blind to their surroundings.
"After stepping into a joint like this," Donatello breathed, "the last thing I need to hear is a sense of doubt from you, Usagi." He ventured another step inside, then turned to look back. They appeared to have come from a solid wall. Reaching behind him, he pushed his hand against it. Nothing. The portal was gone.
"This is not Yume-sama's abode," Usagi proclaimed. He unsheathed his sword and sniffed at the air. "But I fear that we may learn who dwells here soon enough," he added, looking towards a cracked wooden door.
It suddenly crashed open, a score of neko ninja storming in. Donatello only had enough time to grab hold of his bo before one of them threw a smoke bomb towards the confused pair. Coughing, Donatello fell to his knees and swept his bo blindly in front of him. He seemed to have caught at least one of the ninja, but that didn't stop two of them from blindsiding him and wrenching the weapon out his hands before swiftly binding his arms behind him.
"The kame is secured," one of them hissed to his comrades in the darkness. "What of the ronin?" Donatello heard a scuffle to his right and almost felt embarrassed to realize that Usagi was still struggling fiercely whereas he had been efficiently captured. "He is putting up resistance," exclaimed a ninja attempting to pin down Usagi. "Take the kame to Akumu while we get him under control."
Donatello was wrenched up to his feet just as he made the connection. Akumu! He thought. Yume's sister! Usagi's been duped! We're in the base of the evil twin!
The smoke clearing, Usagi could just make out the outline of his captive friend being dragged out of the room by half of the neko ninja in the room. They apparently did not desire to take any chances. He was about to speed after them when he felt something strike him hard in the back of his head. Falling to the floor, Usagi shook his head, determined not to let them overtake him. He did not know how he had ended up in Akumu's castle rather than Yume's, but he was now determined to get Donatello out of there before Leonardo and the others joined them.
Someone grabbed at his arm, and he fluidly slashed his sword to his left, nearly cringing at the cry of pain coming from his assailant. "One day," he told his still-unseen opponents, "when you have learned the meaning of honor, you will be able to use your skill for something more worthwhile than mercenary work." Sensing two others coming in behind him, Usagi turned swiftly and leapt in the air, releasing a double kick that sent the two ninja flying. "Unfortunately," he continued, landing lightly upon the ground, "it would seem that day is long forthcoming."
Paying no mind to the remaining enemy coming for him, Usagi sped out of the room, looking about for Donatello. Thinking he heard something to his right, he raced off in that direction, sword still in hand. He knew that he would need to keep track of where he went. Akumu was renowned for her mastery of grotesque illusion and vicious attacks on the senses. If he and Donatello were split up, and he was separated from the portal through which his friends would arrive, there would be no telling what unspeakable horrors may befall him.
Or, even worse, what would befall the turtles.