Out of all his regenerations, the first Doctor appears to be the oldest. And, in fact, age seems to be the primary reason behind much of the first Doctor's behavior. His initial travels after fleeing Gallifrey were with himself and his granddaughter alone, and they formed a very close bond. When Ian and Barbara barged into the picture, the Doctor was very slow to trust them. Because of this, Ian and Barbara often saw him as selfish and concerned only for himself, willing to abandon them or even harm those who stood in his way if it would be to his advantage. And indeed, this was not far from the truth. But soon the Doctor warmed to his new companions, even if arguments did arise between them on occasion.
Overall, the first Doctor is an extremely grandfatherly figure. At times he comes across as nothing more than a doddering old man, although this is certainly not the case. He calls his companions "my child", "my dear" or "my boy", depending on gender, and likes to insert the word "hmmm?" into his conversation. He frequently mumbles to himself, and stumbles over his words when talking. Poor Ian is often called "Chatterton", "Charleton" or some other variant on his proper name, Chesterton. The Doctor is also subject to fits of giggling, or at least an occasional amused titter. He is easily tired, and may have to stop and rest during a particularly strenuous adventure.
But behind the frail exterior hides a will of iron. The first Doctor can be extremely stubborn, even cantankerous. He absolutely hates to be proven wrong, and often refuses to admit it when he is. He can be stern with his companions, particularly his granddaughter Susan, and he has very high standards of morality, both for others and himself - for example, he refuses to touch alcohol, even as an anaesthetic. When confronted by some horrendous evil, he likes to launch into tirades, and may clutch his lapels with both hands for emphasis. He will not be cowed or beaten, and brandishes a sharp wit to back up his words.
The first Doctor wears a rather somber outfit of black coat, white shirt and checked trousers, sometimes accompanied by a tall, fuzzy black hat. He wears a large sapphire ring on his right hand, which appears to be a source of great power, and often carries a cane which may double as a walking stick and a weapon. Occasionally he will don a pair of half-moon spectacles.
