Banana
Not sure he knows. He did it once because he could, and now he does it if the opportunity arises.
People for me are complex with many layers. Just wanting to replicate that into my character really. There is no overwhelming drive or meaning to understand this. It just is.
Someone earlier in this thread mentioned that they didn't think it important to bracket a PC into a specific alignment, a label if you were. I'm starting to agree.
PC's can be more complex than that if you want. Maybe they should be aligned on their consistent morals (especially in a crisis) added to their current approaches. I haven't worded that eloquently, I'm sure someone can put it better than me.
I guess depending on what day (or time of day) it is I could be NG, CG, CN, LN, TN, NE, LE. I don't think I'm fully LG or fully CE but on any given day I can fluctuate.
It's useful to remember that the alignment system was supposed to exist purely as a convenient formalism to help quickly, briefly summarize a character's behavior and motivations. As I understand it, one of the biggest (if not
the biggest) reasons for it was to make hirelings easier to explain quickly--and to give a very simple heuristic for their general behavior (e.g. Chaotic hirelings would likely accept lower pay or work on "dirty business" jobs, but were more likely to desert when the chips were down). Unfortunately, it also got tied in as a prerequisite for certain classes...which established a precedent for the "straight-jacket" approach so commonly discussed today.
If you'd prefer something a bit more concrete and demonstrative, consider giving Dungeon World a look-see. Alignment in that game follows the same general idea, but instead of "nine points" it's just the five elements thereof (generally speaking). That is, characters are Lawful, Chaotic, Neutral, Good, or Evil--but there's a twist. Each class gives a list of "Alignment Moves" which define a specific behavior. If the DM and/or the group feels like the character fulfilled that particular behavior during a session, they get +1 XP during the session wrap-up (might not sound like much until you learn that levelling up takes 7+current level XP--so you're getting, at worst, 1/16th of a level from that!) There are also some "generic" moves, and given how DW encourages developing your own moves when appropriate, you can really come up with just about anything (if your DM is okay with it).
To give a specific example, the Paladin has two default options.
Good: Endanger yourself to protect someone weaker than you; and
Lawful: Deny mercy to a criminal or unbeliever. My own Paladin is Good, and early on he had
plenty of opportunities to earn that bonus XP. In our second or third session (don't quite remember now, it's been a couple years), he leaped straight into a burning building to save people trapped inside, and got a heartwarming moment with one of the other characters as a result. Nowadays, however, it's actually not very common--but not because his behavior has really changed. It's because generally he doesn't
need to "endanger" himself to protect someone "weaker than him." Usually, if he's leaping headlong into danger, it's to protect another party member--and they're usually not "weaker than him." (Specific exceptions have occurred, though, like an ally being knocked unconscious...while flying.) Similarly, most of the threats that would pay attention to things "weaker than him" are, themselves, significantly weaker than he is--so they're really not a "danger" to him. The character's been max level for ages (we have worked out our own post-level-cap advancement stuff so XP are still worthwhile), so it doesn't really matter that his behavior doesn't ping the official alignment anymore--but it definitely helped to shape the character's initial growth and development.
Similarly, the group's Thief has the alignment,
Neutral: Avoid detection or infiltrate a location. Early on this was quite a challenge, and the Thief's stealthing abilities only came into play every two or three sessions on average. Now, however, the Thief is an absolute
master of infiltration, deception, and silent killing, particularly due to having a cloak of stealth (not a true cloak of invisibility, but when paired with the character's natural hiding skills, it's nearly as good). So, early on, it pushed the player's behavior in particular directions, in a very "be subtle, use panache and wit" kind of way, and led to some damn good roleplaying.
Perhaps, then, it might be useful to come up with a single-sentence "goal" or "ideal" that this character wants to follow--not one he hits every session or even every other session, necessarily, but one that typifies his stance with regard to other people. Is he
Good: Protect the downtrodden from those who would exploit them? Or perhaps
Lawful: Uphold the letter of the law above the spirit? Perhaps he's even
Evil: Take advantage of someone's trust (recognizing that "someone" can include the City Watch)?
You can look here for more examples and some discussion of how DW uses the concept.