Tim had been nervous about Harry's response, but the offer had already been put out there. It would have been rude to retract it now. Harry looked surprised at the offer, which only cause Tim to hope that he would agree. When Harry did, Tim smiled widely.
"Excellent!" he exclaimed excitedly. "Sorry," Tim added, belatedly, for his excitement. "I just don't have many...friends here, that's all." It wasn't said to inspire pity or anything. It was just a fact. Tim rarely had friends that didn't expect anything from him.