Cole slept fitfully that night, tossing and turning in his bed. He saw haunting images of places and people, and he mumbled and murmured in his sleep.
   He found himself running on a wooded mountainside, the sky above dark and cloudy. Trees flashed by his vision. He stumbled down a rocky incline and ducked into a forest cast in shadow. As he raced by the dark trunks, he was aware of cats running with him, flitting soundlessly about the undergrowth. They whipped their tails and glared at him with glowing, pupiless eyes.
   A figure appeared in the distance between the trees, and Cole slowed to a trot. “Philip?” He called.
   Philip turned around and faced him. The dark brown, curly hair was the same, as was his brown eyes and tall, skinny stature. Instead of a laughing grin, though, Philip looked at him with a look of hurt and betrayal. “You forgot about us.”
   Cole stopped. “I’m sorry! Everything changed when I met Sensei Wu—I became a ninja! We had to fight the Skulkin, the Serpentine, Lord Garmadon. . . I’m sorry.” He pleaded.
   Philip looked away. “Liana is by herself. She has no parents, no siblings, only relatives she only met a few years ago. I asked you to take care of her.”
   “I’m so sorry!” Cole repeated. “I had no idea! If I had known you had been. . .” His voice trailed off, then he said. “I won’t forget this time. I’ll take care of Liana, I promise!”
   “Cole!” A voice called in the distance.
   “Not now, I’m in the middle of something here!” He snapped impatiently.
   “Cole!”
   “Can’t you see I’m trying to have a conversation?? Buzz off.”
   “Wake up, ya feather-brain!”
   “No! I need to talk to Philip!” He cried.
   “Wake up!!”
   “No!”
   “ALL RIGHT, YOU ASKED FOR IT!!”
   “OWW!!” Cole shot up into a sitting position in his bed and cried out in pain. “What the heck was that—?!”
   He looked down to see Whiskers sitting haughtily on the bedsheets beside him, licking her sharp claws. He saw his bare arm and realized that three long, red scratches ran down to his wrist.
   “You!” He exclaimed angrily. “You clawed me!! I don’t care what Nya says, I’m gonna—!”
   He stopped, suddenly realizing he could smell smoke. He sniffed the air, then saw that orange light was flickering through his window. For a moment he sat there, eyes wide, then shot out of bed.
   “Fire! The teashop’s on fire!” He shouted frantically.
   Cole burst out of his bedroom and shouted down the corridor. “Everybody out! The teashop is on fire!!” Heart pounding, he slammed the door open to Lloyd’s room, raced to his side and shook him. “Lloyd, wake up! We’re in trouble!”
   “Mmf. . .Wha—whatz go’in on?” Lloyd blinked sleepily.
   “Get out of bed, now! The teashop is on fire!”
   Lloyd shot up from his bed, blinked, then ran down the hallway. “I’ll tell Sensei and Mom! You warn the others!”
   Cole burst into Zane’s room and repeated what he did to Lloyd. “Get up, fast! The teashop’s burning!”
   Zane’s ice-blue eyes snapped to attention. “What did you say??”
   “On fire!! This place is on fire! You need to work on putting it out!” Cole raced out of the room. “Hurry!”
   Jay peeked out sleepily from his room. “What’s all the racket?” He mumbled crossly.
   Cole told him as he swept past him and woke up Nya. Whilst the others ran down the hall to find the source of the fire, he raced into Kai’s room. “Kai, get up! The teashop is—”
   He stared at the empty bed in the dark room. “. . . Kai?”
   Kai’s bedroom was still and silent. His bed hadn’t been slept in; the covers and pillows were smooth and in order.
   “Dang it.” Cole cursed and raced out back into the hallway, his mind on the threat at hand and not where Kai had disappeared to.
   “Over here!” Nya’s voice shouted urgently from the main room, where the tea was kept. Cole dodged into the dark room and was met with spitting flames licking the shelves. The scent of choking smoke and burning tea leaves hit his throat, and he began to cough. Zane and Nya were working furiously to douse the flames, shooting ice and water from their hands whilst Misako threw buckets of hose water. Jay, Wu, and Lloyd were whipping wet blankets and towels at the fire, coughing and wiping their tearing eyes. Cole’s own eyes stung and tears trailed his cheeks, but he summoned earth to choke out the flames.
   Jay, who was closest to the front door, looked to his left and cried out. “Skylor?! What the heck are you—AUGH!”
   Skylor leapt from the shadows and pinned Jay to the floor, brandishing a crude dagger. With a devilish grin she slashed at his chest, but Jay dodged the blow by a hair.
   Cole watched in shock as Kai sauntered in, cackling like a maniac. Cruelty like he had never seen before burned in his friend’s eyes, and he felt an ice-cold chill run down his spine when their eyes met. Kai sneered and shot red-hot flames at the walls.
   “KAI!! What do you think you’re doing?!” Nya looked utterly dumbfounded at the sight of her brother deliberately setting the teashop on fire.
   Kai glared at her, lip curling, but didn’t respond. Instead he turned away and shot more flames at the doorway. The fire blazed and roared furiously, embers flying through the air.
   Lloyd looked stricken, then, brandishing a long katana, charged toward his friend. Kai met him with a snarl and parried the blow with his own sword. The metals clashed whilst Jay struggled with Skylor on the floor. “Could use some help here!!” He cried out.
   Cole raced to Jay’s side and knocked over Skylor, who shrieked furiously and lashed out at him with her dagger. He dodged the blade and slapped it from her hands, and she swung her fists at him. He and Jay wrestled with Skylor whilst Lloyd battled Kai.
   “Have you lost your mind?!” Lloyd shouted incredulously over the roar of the heat. “Kai, what is wrong with you—?! Ah-CHIEE!”
   Kai snarled—literally—dodged his katana, and leapt at Lloyd, slamming him to the floor. Lloyd’s head was knocked harshly, and he struggled to stay awake with a groan and another sneeze. Kai cackled and raised his sword, preparing to strike.
   Cole stared in shock, frozen in place. This has to be another dream, he thought desperately, A nightmare.This can’t be happening. He’s our brother!!
   Misako saw with a horror-stricken gasp what Kai was about to do, then did the only thing a mother could do—flung a weapon at the person attacking her son.
   An inhuman screech split the air, and Kai reeled back, gripping his arm in pain. Cole felt his jaw drop open as Kai’s facial features began to change—his eyes switched from amber to ice-blue. His brown, spiky hair fell into limp, scraggly locks of shoulder-length, gray-streaked black hair, messy and wild. The skin around his eyes and mouth wrinkled to that like of an older man, and when he drew back his lips, spiky fangs reflected in the light of the roaring flames. Then hair—no, not hair—fur began to grow on his face and down his arms. His fingers closed together and his hands formed into wide paws, gleaming claws unsheathed.
   The fabric of the red gi tore and ripped as his body changed and shifted. Hind legs curved and broke free of his pants, and the paws tore out of his shoes. He fell onto all fours, and Cole saw a tail—no, two—furry tails rip free. A muzzle protruded from the face, and whiskers grew from that. The humanoid features disappeared, replaced by the face of a cat. The creature, black-and-white-pelted and roughly the size of a lion, snarled in pain and fury, and glared balefully at Misako with eyes burning with hatred.

Oh, I've read all the books.  I've just never seen the movies.