Donatello made a habit of thinking too much.

He just couldn’t help it. If something was broken he had to repair it right away, because otherwise he’d constantly be thinking about it being broken or the best way he could fix it. Once a problem was in his head he had to solve it or it’d drive him crazy for months. 

He and Leatherhead would spend hours discussing and psychoanalyzing his brothers, trying to find out what made them tick, and how to deal with their more annoying habits. Donatello loved hearing his friend’s theories about himself, especially his personality and mannerisms.

So when Leatherhead pointed out something that Donnie hadn’t thought about him and his brothers, Donnie’s mind went into overload trying to figure it out.

It started with a simple enough question: when did they get their masks?

Donnie could answer that question easily enough.

He explained that the masks were a sign that they were trained in the art of Ninjutsu. Master Splinter had presented each of them with their own mask once they had graduated into the second Kyu of Ninjutsu.

Leatherhead had asked how they had chosen their colours. Donnie frowned, correcting the alligator that they hadn’t chosen their colours. In fact, they all had red bandannas throughout most of their childhood.

He told Leatherhead how they’d just woken up wearing their colours. Master Splinter had told them that they were gifts from his Master’s Master. They had accepted the answer and never really thought about it since then.

Now that Donnie thought about it, it was a little strange that they couldn’t remember receiving the gifts. He’d assumed that Master Splinter had switched their red ones while they were sleeping.

Leatherhead told him that the colours suited them, but before Donnie could question him he was cut off by the ringing tone of his shell cell. 

Donnie had to leave to help his brothers, the question still burning in his mind: why did they suit their colours?

Leo was blue, the colour of the ocean, calm and constant, adapting to any obstacle that stands in the way. That worked well for Leo.

Psychologists theorize that the colour blue is the safest colour, creating a tranquil effect on the mind and body. It was supposed to invoke a feeling of calm and security, making people feel safe in its constant order.

Yes, Donnie thought blue suited Leo well. 

He was the reliable leader, brimming with confidence, ready to take control and do the right thing in a difficult situation. Just having Leo around filled them all with confidence - if everything went wrong, they knew that he could pull them back together and make it right.

Leo’s blue was a direct contrast to Raphael’s red.

Red was the colour of fire and passion; anger, desire, love and energy - it consumed everything around it in its haze of life.

Unlike the calm, controlled feelings that were associated with the colour blue, red let itself lose control, often giving in to its fire and letting itself be consumed and controlled by one emotion over all others. For this reason, it was often associated with anger, consumed with a fiery rage which takes over all other emotions.

Red was the colour of danger and intensity; if someone saw red it was hard for them to notice anything around them until their mind could focus away from the intense veil of fire. 

Raph was definitely red, Donnie couldn’t think of a better way to describe his hot-headed brother.

Donnie’s own colour was purple, a mixture between the two eldest brothers. It was sometimes referred to as the colour of wisdom and compassion. It was said to be the most empathic colour, which fitted his ability to judge his brothers’ moods and emotions.

Purple harnessed the best qualities of its core colours. It was a cool colour, like blue, but tainted slightly by the fires of the warm colours of his other brothers.

He and Leo were the most controlled of the brothers, the ones that made the plans and worked to ensure that everything turned out right. Raph and Mikey were more impulsive, they preferred to throw themselves into a situation and see what happened, then improvise a plan as they saw fit.

Donnie always thought of himself as level-headed; usually able to calm down his brothers during an argument. He guessed that his passion towards his projects could relate to the red that made up his purple, although he didn’t like to admit that he often became fixated with a project or idea to the point of obsession.

Donnie chuckled as he ran across the rooftop towards his brothers, he couldn’t deny his obsessive behaviour. He wasn’t even thinking of the battle that he was running towards because he was so obsessed with their colours.

He caught a flash of orange and jumped into the middle of a full-blown fight. All four of their colours stood out from the sea of black that swirled around the rooftops in the form of the foot ninjas.

Donnie moved on automatic, his body so used to the movements of the fight that he could separate his mind from his actions and continue his train of thought.

Barely registering his younger brother tackling one of the enemies in front of him, Donnie only saw the elegant flow of orange bandanna tails.

Orange.

Orange was the fusion of yellow and red. Yellow being sunshine, life and happiness mixed with the fiery passion of red.

Mikey was definitely passionate, he was the most energetic of the four brothers, with a love for life that brightened the day of anyone he met.

He and Raph were both warm colours, so different yet at the same time both the same. Both were fuelled by the same fire. 

Raph’s fire was more physical; his body was most alive when locked in intense battle. The fire emanating from him was enough to ignite the fighting spirit of the others.

Mikey’s fire was more like a sun, radiating invisible waves of life that affected everything he touched. His bright smile and taunting comments stayed with them all the time, burning a smile onto everyone’s face.

He never seemed to run out of energy, and on the rare occasion that his light faded everyone would band together to get it back.

Orange and blue were opposites on the colour wheel, which made perfect sense when he compared the oldest and youngest of the brothers. Leo’s level head and calm demeanour was a stark contrast to Mikey’s impulsive attitude and rash actions. Two parallels working in harmony.

They all worked perfectly together, opposites and clashing personalities and colours in one family unit that blended together perfectly.

Perhaps that was why they always managed to pull through their battles. Donnie’s eyes ran over the still form of an unconscious foot soldier in front of him.

Black and red; darkness and anger. That was all their enemies had their disposal.

Donnie was knocked off balance by an attack from behind, managing to twist around to fall onto his shell instead of his face. 

His eyes registered a red mask before the dark green skin of his brother. 

Apparently that was the last of the enemies.

“Donnie, ya been distracted all fight. What’s with ya?” Raph frowned, looking down at his brother.

“Nothing, just… thinking.” He shrugged, sitting up and grabbing his Bo staff.

“Donnie. Ya think too much.” Raph grinned, holding out a hand to help his brother to his feet.

Donnie grinned, accepting the hand offered to him. Sometimes he thought his brothers knew him too well.