Life's not fair. That can be misleading.
When Gojyo vanished for an assignation with a pretty woman without leaving a message of some sort, Hakkai fretted and spent far too much time waiting worriedly by the window for his return.
When she turned out to be a demon determined to end his life (hardly surprising, given his sometimes questionable tastes) and rob him of his poker winnings into the bargain, Hakkai took umbrage and helped him dispose of her. Then he spent far too much time engaged in poker and quiet conversation with the disconsolate fool, who soon went on to look for more doubtful female company.
When Goku affected to faint from hunger and the heat in the middle of a scorching afternoon (being a deceptive monkey who had learned to take advantage of the susceptible), Hakkai evinced deep concern and parked Jeep in a shady grove to get him something to eat, upon which the monkey experienced a miraculous revival, too excited to continue the scam. Hakkai merely chuckled indulgently and said he wanted a rest as well.
When a second attempt at trickery earned Goku a well-deserved rap on the head from Sanzo, Hakkai smiled and petted his head while the monkey carped at length about Sanzo's lack of compassion, his cruelty and his bad temper among other faults. Sanzo felt himself quite justified in hitting him again, but that only made him seek shelter behind Hakkai, who looked far too amused at Sanzo's ire for his own good.
When Sanzo tripped and fell into a ditch while absorbed in dire thoughts of retribution, Hakkai laughed. He left it to an anxious Goku to pull Sanzo out and fuss over him until he couldn't take it any more and broke his fan over Goku's hard head. Goku yelped and shot reproachful looks from behind a chortling Gojyo while Hakkai gave Sanzo a cursory examination, and when pressed, healed his turned ankle. He let various scrapes and contusions be, claiming it was to conserve his strength against real need.
When Sanzo found his pack of cigarettes soaked from his mishap, Hakkai smilingly promised to replace it, but took Goku along and spent far too time shopping for other necessary groceries, and likely spent too much of Sanzo's credit feeding the monkey. Meantime Sanzo fumed and suffered from withdrawal pangs, and Gojyo went out gambling to avoid him.
Sanzo resented the disparity bitterly, falling into an ever darker mood, and once Hakkai finally returned with his cigarettes, he submerged himself in a haze of smoke so thick that even Gojyo complained, and Hakkai opened the window to let it out, stealing puzzled sidelong glances at him. Goku insisted he needed more food to repair the damage to his lungs, while Gojyo muttered snide comments about his moods. Sanzo only puffed harder in retaliation.
Hakkai looked concerned, and being sensible and considerate, gave Sanzo a wide berth in which to sulk peacefully, so as to refrain from vexing him further. Goku and Gojyo took no heed, and entered into a rousing argument, whereupon Sanzo drew his gun and Hakkai hastily ushered them out. He paused at the door, obviously considering taking himself out as well. Sanzo was even more annoyed.
Fortunately, by some mysterious sense, or possibly because he wanted some peace himself, Hakkai came back in, smiled hesitantly, and buried his nose in a book he'd not had time to read lately.
Sanzo stubbed out his cigarette and unfolded his newspaper. They read in companionable silence, and Sanzo was pleased to find a glass of water waiting by him when he wanted it. Such small attentions he had to make do with, because Hakkai had enough on his hands with the others, and thought Sanzo old enough to take care of himself for the most part. Sanzo relaxed, enjoying the rare moment of shared peace, and Hakkai looked sober and wistful.