If the HLP pair were to turn non-hetero, they would probably get married in a heartbeat. However, if only one half of the HLP pair turns non-hetero, it will potentially make things mighty awkward palmtree.
Going on lunch/dinner/brunch/happy hour dates, playing wingman/wingwoman, going on vacations together at least 3x a year, saying/thinking/doing the same things, being crazy fans of team/places that you do not actually like/live in together, indulging in each other's vices (i.e. shopping, eating, drinking), obsessing over people who should not be obsessed over but are allowed to be because you are HLPs and no one else understands each other like you do, referencing each other on Yelp reviews.
Scrub 2: Hell no, HLP is finally going to show up to roll house