Quote 1
"Think before you answer, for it shall be done as you decide. As you decide, you shall be left as you were before, and neither richer nor wiser, unless the sense of service rendered to a man in mortal distress may be counted as a kind of riches of the soul. Or, if you shall so prefer to choose, a new province of knowledge and new avenues to fame and power shall be laid open to you, here, in this room, upon the instant; and your sight shall be blasted by a prodigy to stagger the unbelief of Satan." (9.28)
Dr. Lanyon can either take comfort in this kind act, or choose to come face-to-face with evil.
Quote 2
"We had," was the reply. "But it is more than ten years since Henry Jekyll became too fanciful for me. He began to go wrong, wrong in mind; and though of course I continue to take an interest in him for old sake's sake, as they say, I see and I have seen devilish little of the man. Such unscientific balderdash," added the doctor, flushing suddenly purple, "would have estranged Damon and Pythias." (2.9)
Dr. Lanyon and Dr. Jekyll are estranged because they disagree over science. This suggests an initial frailty to their friendship in contrast to the strength of Lanyon and Utterson’s relationship.
Quote 3
Upon the reading of this letter, I made sure my colleague was insane; but till that was proved beyond the possibility of doubt, I felt bound to do as he requested. The less I understood of this farrago, the less I was in a position to judge of its importance; and an appeal so worded could not be set aside without a grave responsibility. (9.10)
Dr. Lanyon complies with the letter’s requests more out of curiosity than out of loyalty to his friend.