I'd like to bring to note a currently obscure individual who might just prove mildly important to future events especially in the Reach and bring forth real world parallels to support my theory.

The Individual

• Talla Tarly is the second child of Randyll Tarly, lord of Horn Hill, one of the most powerful lords in the reach and his wife, Melessa Florent.
• She is also the oldest of Samwell Tarly's three younger sisters and the only one who is named, so maybe George has plans for her.
• She is also second in line to inherit Horn Hill as of Samwell's disinheritance. Her younger brother, Dickon is the current heir to House Tarly. He is marching to war with their father, Randyll.

Current Events and The Possible Future

• Talla's mother, Melessa is the supposed current heir to House Florent, as her younger brother Alekyne Florent, the current and attainted lord of Brightwater Keep is not mentioned to have any children. Hence, as the oldest daughter, this gives Melessa and her progeny a strong claim to Brightwater.
• However, Brightwater has been granted to Mace Tyrell's second son, Garlan. But the Florents still hold the castle albeit under siege. This obvious land grabbing move by ambitious Mace, could have been taken as a slight by Randyll Tarly whose wife has the stronger claim. Another possible slight would be Mace Tyrell taking credit for the defeating Robert Baratheon's army during the Battle at Ashford, even though Randyll led most of the vanguard.
• These slights might push Randyll Tarly to support Aegon Targaryen (most likely false) in the battle at Storm's End or by open the gates of King's Landing to Aegon's forces. If the Battle of Steel as fans call it is written to parallel the real-life Battle of Agincourt, many soldiers, noble and lowborn alike in Mace's army will be executed by Jon Connington, who might choose to be more brutally decisive given his greatest regret at the Batlle of the Bells. Here is a link to a post that discusses this in more detail.
• However, there is a bigger problem for the Reach at the main coastal regions, Euron Greyjoy and the Ironborn. If all goes well for Euron, he defeats the Redwyne Fleet, sacks Oldtown, and he gets his hands on one of Daenerys Targaryen's dragons, the Reach will find itself in peril. If Aegon VI reigns for a time, he might march his army to retake Oldtown and liberate the Reach. Randyll and Dickon who is marching with him, as well as Aegon's other supporters might join him, after all the Tarlys are "First in Battle". However, they will no doubt face obliteration at the hands of Euron and his newfound power. With her father and brother dead, and her older brother disinherited, Talla might just find herself as the lady of Horn Hill in her own right, and a possible heir to her mother's claim.
• Talla's brother, Samwell is in Oldtown. Some readers have theorized that he might make his way to Highgarden and meet with Willas Tyrell, the new Lord Paramount of the Reach, who would be trying to stabilize the Reach, with his mother, and grandmother as advisors, and Garlan working to take back the Shield Isles. I believe from there he might make his way home towards Horn Hill.
• With the Reach unstable and the Tyrell's in need of allies to hold back Euron's onslaught, Willas might send Samwell to Horn Hill with an agreement to pardon House Tarly, in exchange for an alliance and the aid of the Tarly's remaining military forces. What better way to bind this alliance than a marriage. Willas is one of the most eligible bachelors in Westeros and was once presented an option to Sansa Stark. One of Talla's younger sisters could do, but personally I think Talla is the better option.
• The marriage could also possibly gain House Tyrell the support of house Florent due to kinship with the double heiress, in retaking the Shield Isles, Oldtown and maybe the Arbor if it falls, and bind the wounds of the Reach to hold back the Ironborn. at least until Daenerys possibly arrives in Westeros and brings down Euron in the second Dance of the Dragons.
• Talla becoming lady of Horn Hill, marrying into House Tyrell and still continuing the Tarly name through her possible children would be an ironic salt on the wound to Randyll who worked incredibly hard at great cost to get a male heir fitting to his image. It would also be a nice parallel to his attempt to gain the Mooton lands for his house, by marrying his son to the heiress to Maidenpool.

Historical Parallels

• Two more historical parallels for this especially in regard to the Reach pulling inspiration from France, could be two noblewomen in real-life French history who were at some close point in time rulers of two wealthy and powerful duchies in their own right. Anne of Brittany, Duchess of Brittany and twice queen consort of France, and Mary the Rich, Duchess of Burgundy.
• Famously, Burgundy, and Brittany both maintained nominal independence from the Kingdom of France until Anne of Birttany and her daughter were married into the ruling dynasty at the time, absorbing their lands into France, and much of Burgundy was forcibly taken during the War of Burgundian Succession.
• Their support both proved vital for each of their husbands rise in power, during their respective reigns.

That's about it. Please let me know your thoughts below, and how you think things could work out for this character, and House Tarly as a whole. Thanks for reading this far.