The lines are: "Faith kept me back awhile," replied the young man, with a tremor in his voice, caused by the sudden appearance of his companion, though not wholly expected."
The young man knows who his companion is given that when he saw him, it caused a tremor in his voice given that he suddenly appeared and was not expected.
Out of those lines, we can infer that he is not happy or annoyed, but that he knows who he is.
Airbags, when activated, give off too high amounts of force than a child could withstand. They could break the child's ribs or other body parts if it goes off, or give them a concussion. Therefore, it is best to either turn the airbag feature off or, better yet, have the child sit in the back seat.
