"Show, don't tell" is always the most relevant advice. If the background is important at all, then it should surface in the real world via books, statues/ruins, cultures and common sayings, etc. You know, how we find stuff out about our world and real life. Instead of infodumping, have it come in from various directions - someone shooting the bull in a tavern, an old lady met on the road, an abandoned shrine with an inscription, a couple books in a murdered mage's satchel. Any schooled PC, you can give some of it to them as "Well, you know from back in the Academy that the Knights of Northrop always ride back horses because..." Look for relevant knowledge type skills on the PCs' character sheets as a channel for that. Since you're using somewhat archaic language I assume you mean in a medieval fantasy type game but of course in a modern or future game you have TV, Internet, and ninth grade history class to add to the mix.
I would be concerned with the "pet DMPC" approach because it seems like it would tend to discourage PCs from actually exploring and trying to find out information, out of the assumption that relevant info will be dumped on them. Make them piece it together, seek out sages or other people that might know something, etc. Converting a party into proactive mode always engages them more and gives opportunity for plot hooks/quests.
Also - if it's not relevant to the plot at hand, take a light hand with it. I know, as a DM I want to get across the Many and Varied Wonders of my Campaign World (tm) too, but DMs tend to want about 300% more of that than the players do. I sometimes prepare a world/campaign briefing sheet for my players ahead of time to convey lore they should all just know, and have learned the hard way that if it's more than a couple pages they're not going to read it.