The way that Castiel just appeared as soon as Dean called definitely said something about their friendship. Dean was brought up as a warrior, a soldier out to protect his family. When Castiel arrived he had something more to fight for. Castiel would protect and serve Dean, as would Dean to Castiel.
The Doctor noticed these little characteristics in Dean. He guarded himself a lot much like the Doctor, due to being hurt and having to remain strong. The Doctor had seen death, destruction and had recently lost his dear Pond's. Keeping distracted was the main reason he called on Castiel, and Castiel knew Dean would spark faith back in the Doctor as Dean sparked faith back into Castiel.
And so far it was working. The Doctor had spring back in his step; he bounded around the San Juan national park like a baby deer. His eyes were alight with excitement. Castiel enjoyed watching the Doctor frolic around. It reminded him of the months that he spent in the hospital. Carefree and content with the world at last.
Dean slammed down the boot on the Impala, brandishing a sharp knife. Sam also had a long thin blade in his belt; in his hand he gripped a shotgun. Crocotta's weakness was a sharp object pierced into their spine, and the boys set out to do exactly that.
"I don't like weapons. Especially that gun." The Doctor shot a troubled look towards the gun in Sam's hand. Sam put the gun into his jacket, so that the Doctor wouldn't have to see it too often. Castiel roamed around the clearing that the Impala was parked in, watching bugs fly past and a bunny hopping into a nearby rabbit hole.
They couldn't see the sky very well above them, the tree canopy looming dark overhead. The twisted, thick trunks of the trees contortioned into each other. Dark green mold appeared speckled over the rotting roots in the ground. The floor of the forest was concealed in leaves, which gave a slight crunch whenever they placed a step. This place could seem magical but to the two brothers, the angel and the alien, it was the most dangerous place of all. As the men stepped off into the forest, Sam and Dean kept a weary hand on their weapons.
The beginning of their walk into the forest started in silence. The Doctor looked nervous, holding his sonic screwdriver out in front of him. Castiel examined the wildlife closely - the birds flying in fear whenever they stepped too close, the distant sounds of a large herbivore running away. He marveled at the nature around them. Sam and Dean kept watchful eyes ahead, and walked as if they were bracing themselves for anything that could jump out at them.
"So Doctor… you're not an angel. What are you?" Sam murmured towards the Doctor, who jumped slightly at the sudden conversation.
"I'm a Timelord. I'm not from this planet, my planets much, much farther away. None can access it. Trapped inside a time lock. I travel the stars, time and space. It's fun when you have someone to travel with." The Doctor smiled to himself, thinking fondly of the beloved couple he gravely lost.
"Who are you travelling with now?" Dean asked curiously. The Doctor stopped in his tracks, and the others stopped with him. He looked solemnly into the forest, his facial expression showing complete melancholy.
"No one. I lost my Pond's. They're not the first. I had others. But everyone leaves. Everything ends." The Doctor dejectedly responded. Dean cleared his throat and gave an empathic touch on the Doctor's shoulder, as he marched on ahead.
"We need to be careful of the Crocotta. They can appear in any form of someone's lost loved one, and it will suck the soul right outta ya'." Dean spoke quietly but confidently, "They're also really fast. Sammy and I faced one a few years back. But it used telephones. Smart asses."
Their walk continued on for a few minutes until a faint call was heard in the distance, among the sound of the humming bugs and the twittering from the birds. Dean held his arm up to stop the group.
"Did someone hear something?" Sam whispered, and the group froze. They cautiously looked around and strained their ears for another sound. The call came again, but this time closer.
"It sounds like… a chick." Dean sounded confused as he told the men. The Doctor felt as if both his hearts had just stopped. He thought he recognized the voice.
"Come… To Me…" a female voice called from the tree's in front of the Doctor. His eyes began to water and he gripped Castiel's arm tightly.
Crunching of the leaves on the ground came closer and closer. Birds flew away in horror. The figure of a woman started to emerge from the thick fauna in front of the Doctor.
"I know who this is." The Doctor's voice trembled as the female approached and stood still in front of the Doctor, repeating, "come to me" in a broad, Scottish accent.
"It's Amy Pond."