Unfortunately, the full quote isn't a real thing. "Blood is thicker than water" date from the 12th century, while the "blood of the covenant" date from the 1990's. In general, many of the supposed "full quote" are also later inventions.
That said, yeah, Hongo needs people who cares about him...
It's just a short arc to develop side characters, so it's probably the end of it for now. We will probably have another one down the line, but now we either return to the main story or we focus on someone else for 1-3 chapters.