Although not as outrageously smutty as some yaoi, this manga is absolutely delightful. As the book description states, Pathos is the story of 2 men (vampires) raising a human child. The younger of the two men, J, is drawn to the boy's blood and desperately tries to resist the temptation so he doesn't kill him. This gets a bit complicated, though, as the boy (Ace) finds himself more and more attracted to J and tries to seduce him. This all leads to a shower scene with J finally sucking the teenaged Ace's blood and almost killing him. The older vampire, King, comes home in time to save the boy and explains to J that for a vampire, bloodust equals love. In other words, J is in love with Ace.
Since vampires suck blood instead of having sex, there's plenty of hot and heavy embraces with close-ups of a fang entering someone's neck.
There's also an awesome scene with King and J, where King interrupts J's pickup of a victim and pays the victim to have sex with J in front of him. Technically, a vampire can't get it up, but King's excitement in watching is obvious by his intent eyes and lengthening fangs. Rawrr!
Overall, a great book - nice art, captivating characters, and plenty of teasing that will leave you wanting volume 2 right away.