Disclaimer: I do not own 'The Hitchhikers' Guide to the Galaxy' in any way, shape or form.
Something decidedly odd was going on. Granted they were in a ship with an Improbability Drive and granted it was normal for weird things to happen (an oxymoron, I know) but this was decidedly, definitely odd. Arthur was smiling.
The moody, whiny, complaining, useless waste of space, feeble excuse for a monkey was smiling. At Zaphod. And he was still smiling at Zaphod as he got up and walked (somewhat lightly) out of the room. The self-named hoopiest frood in the galaxy shook his heads at the idiocy of the Earthman and returned his adoring gaze to the large handmirror he had been staring into- an activity that was always distracting, fun, wholesome and worthwhile… for Zaphod.
So engrossed was he in his own countenance that he did not notice the slow and strangely ominous approach of the third occupant of the room. That was, until his mirror was violently wrenched out of his hands and hurled against the opposite wall. As it shattered, Zaphod leapt up, alarmed, and looked down into the tempestuously angry Earth-sea-blue eyes of his semi-cousin.
"Ford? You zarking moron, what, by Zarquon did you do that for!" he yelled, drawing himself up to his full height, both heads snapped towards the offender. The other Betegeusian seemed unimpressed, continuing to glare balefully at him.
Zaphod flung his arms out in exasperation. "Well?" he demanded when Ford didn't answer.
The shorter man reached out and grabbed him by his lapels, yanking him down so they were face to face. "If I were you, mate," Ford growled, every word dripping with enough venom to wipe out an entire planet, "I'd be extremely careful about who I smiled at."
Ford released him, dropping him contemptuously to the floor in an untidy heap. "Just watch yourself, Beeblebrox," he warned before storming off, waves of anger fizzing out of his every move. Zaphod watched him go, completely bewildered. What had that been about?
The 'Hitchhiker's Guide to the Galaxy' says the following about Betelgeusians:
Due to their carnivorous ancestry, beings from any planet in the vicinity of Betelgeuse are extremely protective of anything they view as 'theirs'. Though they are normally perfectly accepting of hitchhikers and quite happy to give them a lift, it must be noted that hitchhikers who find themselves on a Betelgeusian spaceship uninvited are advised to immediately hand over all alcohol to pacify their hosts.
They are also advised to keep away from anyone a Betelgeusian is romantically involved with. Any sign of romantic favour between their partner and another being is seen as a threat. Betelgeusians are renowned for eliminating threats by any means necessary.
N.B. Signs of romantic favour include; touching; hugging; kissing; waving at; smiling at; winking at; passing an object to; asking the time of; sitting next to when there are no other seats; or generally being within a five-mile radius of the aforementioned Betelgeusian's partner. Be on your guard.
P.S. Just in case its not clear, Zaphod would normally understand Ford's actions, but he is unaware of the ...closeness... between him and Arthur. Also, I have no idea where this event occurs in the timeling of the series. Feel free to place it where you will.