But we get to see Pi being a sloppy freeloader. So we know what Rick knows, with no explanation of why he can't use his words with Alexis, but we have no Alexis PoV, so we don't know why she can't tell he's a) sloppy and b) freeloading, both of which behaviours seem pretty obvious.

That is why it is hard to tell if it is poor writing insofar as Castle could be saying, "I don't like the belt left on the floor," but instead is seeming to say, "I don't like this guy you brought home (look, he left his belt on the floor, that's why I don't like him, I knew when you brought him here he would do that because boy and hair and woowoo)." I mean, if they intend for Castle to not like Pi and therefore not handle things rationally, they are doing a bang-up job.

I agree with ita ! that the writers have given absolutely no reason for the viewer to like Pi, and I don't think that's just a miscalculation on their part like, say, Zane on Eureka seemed to be (which I also thought they did a pretty good job of fixing later on). Alexis comes off looking oblivious at best, if not in full blown denial of Pi's myriad flaws.

Then again, IRL I've known some very smart people to do unaccountable things romantically.

Then again, IRL I've known some very smart people to do unaccountable things romantically

And I worry that she's going to a) be shown wrong b) be shown right. I only hope they both accept the other had some points.

I enjoyed their puzzle-solving shenanigans more than any of the movies they name-checked (unless there was, and maybe even in addition to, an Indy reference). Have a look, Dan!

What, exactly, are Pi's myriad flaws? Are they flaws or just character traits or life outlook?

I think we need to come up with a list to debate.

Are they flaws or just character traits or life outlook?

I couldn't start to answer your question without knowing why those are mutually exclusive.

I'm hoping all this is leading up to building a stronger connection between Beckett and Alexis. We've had plenty of clues that Beckett declared her independence in all kinds of ways that her parents didn't approve of. She seems to understand that this is just Alexis trying to become her own person.

I don't think Castle is wrong because Pi is ridiculous and I don't think Alexis is wrong because, well... she's 19 and Pi isn't a bad person. I also don't think Pi will last too much longer because he is so very ridiculous.

Some of the things that Castle does not like about Pi are not necessarily character flaws, but just a very different outlook on life. These are the things that I can think of that count as potential warning signs for character flaws on Pi's part:

1. Whatever the heck happened to his passport/Amsterdam home. Now, there may be a genuinely innocent explanation, but it seems at best to indicate some flakiness.

2. Leaving his personal possessions strewn about such that Rick stepped on the business end of his belt buckle. While being a bit messy is hardly the worst sin, a little safety consciousness is a big virtue especially in someone else's home. (I say this as THE person who can never remember to shut cupboard doors.)

3. Not having a job when he met his girlfriend's dad. This could be a sign of a gold-digger. The facts that he has a very good reason to be between jobs, having just come back from Central America, and that he managed to get a new job fairly quickly may tell against it, but that does not take way the bad taste in the mouth from the first impression.

4. He is awfully New Agey, very surfer casual in how quickly he was ready to just crash on his girlfriend's couch. That is all outlook/personality. I mean, that is the part of him he has used most to contribute to the household - breakfast smoothies, Rei-ki. This seems to bother Castle as much as anything I consider to be a genuine problem.

Pi thinks spelling isn't important. This is a character flaw.

Wow, flaky and messy and not super considerate at 19.

We've seen all of that but also generally goodheartedness. Clueless, and intensely annoying to Castle? For sure. Not in line with his vision of Alexis? Absolutely. Worse than that? Not really. He needs to get over this shit.