I touched on Hyrum in the earlier post, named him as Merry from the LOTR, and then promptly forgot about him. That seems to be the way of things with Hyrum as to how Mormon history has treated him - he is hardly mentioned on his own without Joseph, and when he is, Joseph still takes the lion's share of attention.
So, I will remedy that, and give Hyrum some overdue attention.
First, I actually find that I don't have much to say on the Merry connection part, other than perhaps a few observations. I would call out and emphasize what Eowyn said to Eomer about him after waking in the Houses of Healing:
"Eomer, you shall make him a knight of the Riddermark, for he is valiant!"
And that is what Hyrum-Merry was and is - valiant, steadfast, and never one to abandon his family and friends in need.
His temperament seems to be a nice compliment to Joseph-Pippin in both of their lives together. Pippin just couldn't keep himself out of some kind of trouble or impulsive behavior, even if well meant (e.g., dropping stones down wells in Moria, stealing glances in the Orthanc Stone, pledging fealty to a Lord he'd literally just met, etc.), a trait he later as Joseph would still lament - a lightheartedness to things that he sometimes felt should be taken more seriously.
Hyrum-Merry, on the other hand, is a bit more of a planner and thinker - more deliberate in his actions. Merry is the one that actually studied the maps in Rivendell and so knew generally where they were following their escape from the orcs (while Pippin just couldn't be bothered). As Hyrum, Joseph would look to him and take his advice on many things.
And, of course, there was Merry's his selfless act of heroism with Eowyn against the Witch King. His driving thought was that she should not die alone, unaided.
This same trait, of course, is what led him to be in Carthage with Joseph and to die with him.
But here I am again talking about Hyrum-Merry in the context of Joseph-Pippin. Let me briefly give him his another story that is his own:
The same being who was born as both Hyrum and Merry, was also born as Nephi, the son of Lehi, whose account is found in the opening chapters of the Book of Mormon.
I won't recount Nephi's story, as his seems to be most well known in Mormon scripture (and the most controversial) but will say one thing about the future.
Nephi's retrieval of the Brass Plates is an event that will become evermore important in a coming day. As he recounted in his reasoning for killing Laban, he knew the Brass Plates were important, but didn't know the full extent as to why until he and Lehi had a chance to look through them. On those plates they found a correct account of the creation of this world as well as many prophecies. He initially had assumed that he was gaining these plates for the benefit of his own children, but Lehi and later Alma discussed the much larger purpose of those plates in saying they (or the words on them) would one day go to every nation and people and reveal mysteries to all Men.
As Nephi is the one that did this heroic deed (as well as having to do other things that he would have rather not done), it will be him, the same individual, who will have the blessing and privilege of fulfilling the prophecy and mission that the Brass Plates were preserved for.
I have written before of a stone and a seer while will reveal words from that stone. The Brass Plates are additional words that will also come forth in that same period as the words on the stone - adding an additional witness as to the accuracy of those words, as well as restoring other lost stories and truths. Meaning, Merry-Nephi-Hyrum (and there are other names for this being also, I believe) will work in partnership with the seer in bringing redemption and salvation to the Family of Light - which is a family they both belong to.
This of course means that Hyrum will have another go around on this Earth, and may in fact already be doing so.
As Hyrum was told in what is now D&C 11, he was to "wait a little longer until you shall have my word" and "seek not to declare my word, but first seek to obtain my word, and then shall your tongue be loosed". The words on the Brass Plates are the words Hyrum was and is to wait for, and once he has them, he will speak great things "with the Power of God, unto the convincing of Men".
Great things are meant to come forth, and it will be great beings who will bring them. The being who has been known as Merry, Nephi, and Hyrum and other names besides those, is one of the greatest.