Personally, I like to think of Ambarussa that "the youthful pair" of the Silmarillion that many fans would fall in love with. To me, they are the Merry and Pippin from Lord of the Rings, or the Fili and Kili from The Hobbit; both cheerful and beginning as the children, but still fierce and open-minded fighters that would do anything for their loved ones, no matter how much they'd question said-loved ones' choices.
Albeit, this "youthful pair" ends up having much more tragic circumstances than either of the previous ones for the remainder of their adulthood, but despite that, I still like to believe Ambarussa are cheerful and compassionate by nature, with some curiosity and reckless humor to spare.
-Pityafinwë (Amrod) and Telufinwë (Amras) Ambarussa were born sometime after one or all of the Silmarils were created (either around Y.T. 1450 or Y.T. 1490); either way, it's the same "Valian Year" their father was exiled to Formentos; during that time, they were either still children, barely entering their tweens, but were already considered great hunters among the elves of their young age in Aman.
-Ambarussa were always the babies of the family.
-They are two of the most cheerful and childlike of the sons of Fëanaro.
-Alike in face and mood, they resembled their mother Nerdanel the most out of all her sons, inherited all her looks and temperament, including her red hair and freckles.
-As they grew older, however, Pityafinwë had a darker shade of red hair (due to Feanor's dark hair) and Telufinwë started showing more hints of his father's adventurous and fiery spirit, making him the bolder and more outspoken of the twins.
-Everyone loved them dearly, even for all their infamous mischief that labeled them the "Twin Foxes of Finwë."
-Throughout their youth, Ambarussa were also considered short in stature compared to other elves, always being the smallest in their family (including Tyelperinquar as an adult, later on), which was the opposite of how their oldest brother, Nelyafinwë Maitimo, was always among the tallest of elves.
-While this didn't necessarily help them attract other elves the way their brothers could in terms of courtship, their young faces also making them look forever boyish for their age, their lithe forms helped them be more light-footed and stealthy, becoming better climbers and expert hunters, both in the woods or sneaking around to spy or set up pranks unnoticed.
-One twin's mother-name was Umbarto ("Fated One"), but was quickly changed to "Ambarto" by Fëanaro to change that fate.
-It remains uncertain which one of the twins keeps that name, so they take turns using it, just like they share the name "Ambarussa."
-In the end, it was Pitya who claimed the name Ambarto (or Umbarto) as his mother-name since his younger twin had been given an epessë name by others (also, as the older twin, he would rather let "fate" claim him than his beloved younger, if their mother's prophecy ended up coming true).
-Telefinwë's epessë nickname became Minyarussa, meaning "first-russet", mainly because his hair shined a brighter, fiery red than his twin's and therefore was the first of the two to stand out in appearance.
-Like how Curufinwë Atarinkë was considered their father's favorite for having the most in common with him, the twins were considered to be favored by their mother, due to her ever-constant coddling and worry.
-Their older brothers don't mind so much, since they too enjoy the company of the twins, spoiling and worrying over them in their own, different ways.
-Like the rest of his family, ever since they had been born prematurely, Fëanaro loves his youngest twin sons with a fierce protectiveness (especially after hearing his wife's foreboding prophecy); but by the time they were toddlers, all three of the Silmarils are finished and Melkor has already been released, so he neglects to pay much attention to them when absorbed in his work at the forge (either secretly making weapons or losing himself in the Silmarils' light).
-Because of his constant absence and ever-changing moods, it was either their mother or older brothers that end up raising the twins together, for the most part.
-For their whole lives, their oldest brother, Maitimo, had been more like a father to them rather than just their oldest brother, having always been there for them when Fëanaro hadn't in recent years; since they were the only brothers whose birth he actually witnessed (back when he had to support Nerdanel before Fëanaro finally arrived in time), the feeling became entirely mutual for him from the moment he first held the tiny newborn Pitya before Telvo followed.
-After a very difficult birth that Nerdanel and the twins barely survived (thanks to Fëanaro sharing most of his fëa in desperation at the time), because they were premature and weak, they all learned that the twins each had only half a portion of the normal amount of fëa an Elfling was born with, and that only became whole with the spiritual support of one another.
-Because Nerdanel already had five children before them, all provided with strong fëa, her body could barely provide even the necessary amount of fëa for one baby, never mind two at once (there was a reason Elven marriages never had more than five children).
-Since neither she nor Fëanaro sensed two babies, as their fëa were so similar it seemed whole, neither one had been prepared to give more fëa, and the pregnancy would have likely costed Nerdanel her life if Fëanaro hadn't been there to support her in their marriage bond.
-Since these identical twins were born mentally and spiritually linked, they had to be inseparable in body and spirit (meaning if one twin died, chances were that the other would soon follow, out of heartbreak or a very fragile fëa, if not constantly nurtured).
-Since that day, especially with Fëanaro having then begun showing more signs of his more ill-tempered behavior and paranoia, especially after recently hearing of Melkor's release, Maitimo made a promise to his mother, and to himself, that he would protect his baby twin brothers with his life.
-Kanafinwë Makalaurë finds them to be the only younger brothers he has enjoyed taking care of, since they have genuinely been the nicest to him and they shared the same gentle temperament.
-As little children, with their mischief and surprising intrigue in romance, they even helped get him closer with the maiden he courted as they both looked after the twins while practicing music together (and they would soon get married during their time in Formentos).
-Since he and his older brother would often take turns in helping raise their little brothers, family members would often joke that Makalaurë was more of a "mother-hen" when comparing his parental practices to Maitimo, his personality being very much like Nerdanel's.
-Turkafinwë Tyelkormo had become their mentor and protector for their shared interests in hunting in the wilds of Aman.
-Before the twins were born, Tyelko and his Valinor hound, Huan, would normally either wander off on together to hunt Oromë, spend time with Irissë, and occasionally spend some quality time with Curufinwë, but would isolate himself from the rest of his family since the time he reached his majority. He too feels recently neglected from Fëanaro's affections, especially after Curufinwë was born.
-Because Ambarussa had been widely known for their mischief and sneakiness since they were babies, also having shown signs for their love of nature, herbs, and wild animals, they followed Tyelko around to the point when he started taking them on his hunting trips by the time they were in their early thirties (ten to twelve years-old in human years).
-Through this, they grew close to him and brought the softer, tamer side back out of Tyelkormo, even pulling him and Irissë back to society every once in while to spend time with the family in Tirion.
-Through Tyelkormo, they got to know their cousin Irissë (whom they saw as a big sister), and through her, they met up and became fast friends with her younger brother Arakano, who was only ten or so years older than them.
-With their fair-haired older brother, the twins learned archery, how to set traps, how to mimic animal sounds, and even picked up a fast interest in using herbs for medicine, allowing them to study many techniques in healing.
-Ambarussa had also become insistently close to their brooding, dark, and bipolar older brother, Moryofinwë Carnistir, who prefers solitude and distance (and has a unhealthy fascination to darkness), but secretly holds a great affection for his brothers and a great admiration for his father.
-While it's Carnistir that the twins seem to bother constantly with jokes and pranks while he is working (second to Curufinwë), they have no problem listening to him or channeling his temper.
-While not having much in common, they share freckles and Carnistir feels he will do anything to make sure Ambarussa stay safe and happy.
-They have a testy relationship with Curufinwë Atarinkë, who would take turns with Carnistir babysit them, but he still loved them as his only little brothers and would look after them in subtle ways, as he would for all his brothers. The twins were also the fun young uncles who would take care of his son later on.
-Ambarussa were often friends with Arakanò and Artanis, who were both the youngest in their own families under Nolofinwë and Arafinwë. They are also, through Artanis, well-acquainted with Olòrin the Maia (the future Gandalf the Gray), who had a soft spot for creatures and things that were merry and full of mischief.
-At a very young age, Ambarussa ran away multiple times in their childhood, causing quite a few scares and trouble-making. This happened more often after Nerdanel, their mother, became estranged from their father, and they would take it upon themselves to find her during the times when Fëanaro wouldn't allow them to go see her.
-They were still young boys when they were required to follow Feanaro into exile at Formentos along with their brothers, because Eldar Law demanded (according to Feanaro) that the sons of an estranged couple remain with their father (and even more so under the High Prince).
-Nerdanel reluctantly agreed, since they would have already come-of-age by the time their father's thirteen years of exile were over, the twins needed "ellon' in their lives more than ever (which included their grown older brothers).
-Fëanaro eventually allowed them to stay with her a few weeks or months at a time, so long as they were with at least one of their brothers (in this case, it was always either Maitimo or Makalaurë (the only other brothers who missed their mother enough to go visit her) and that they returned to him no later than planned.
-Ever since Nerdanel left, and because of the twins running away, Fëanaro's paranoia developed an incurable fear that he would lose his sons forever, even to his own wife.
-As much as the twins adored their mother, especially Pityo, even visiting her the most alongside either Makalaurë or Maitimo, they began to gradually develop some bitterness towards her after hearing their father and middle older brothers complaints about her abandoning her family, not even willing to come for her youngest while they were still elflings.
-Out of the twins, Telvo felt closer to their father than Pitya did, who rather felt closer to their mother due to his personality being more timid compared to his twin's.
-During the last years of their exile, when Ambarussa were in their forties (fourteen to sixteen in man years), Tyelperinquar was born, and it was the twins whom acted as big brothers to him, and even helped keep him cheerful and innocent when Curufinwë was busy or just typically in one of his moods.
-The twins are slightly more wary of Fëanaro than their brothers, but would dare not disobey him, more for their older brothers' sake than their own father.
-Like Makalaurë, the twins were lured by fear and peer pressure into swearing the Oath.
-Not only did they do this because their father has, but because they would follow their eldest brother, whom they both looked up to as another father and role model, who took the Oath after Curufinwë, then followed by Carnistir, then Tyelkormo, and finally Makalaurë, who only did it because he wouldn't forsake his brothers.
-The twins were only a few years short from coming-of-age (which is fifty, seventeen or eighteen in man years) when they swore the Oath with their father and brothers.
-Other than being one of the first to swear the Oath himself, Maitimo will look back on this decision, thinking of when he encouraged his baby twin brothers to take the Oath alongside him for their father's sake as one of the biggest mistakes he made of his life, having single-handedly broken his promise to Nerdanel for letting this happen.
This is just a bullet-point summary of some planned stories involving Ambarussa that I HOPE to write in the near future, when I have the time. They're not fully written stories yet, but these are just how I view Ambarussa, since there is so little information about them other than their appearance and specialties. It might even be a little OCC, but just bear with me; these aren't final. Let the games of Character Study begin!
The first chapter is just a profile introduction of the twins, their birth, their barely distinguishable personalities, and their relationship with their closest family members. The next chapter will be concerning the Umbarto Arc. If you're fans of Ambarussa, thanks for reading:)
Fëanaro = Fëanor
Maitimo/Neylafinwë/Neylo = Maedhros (epessë: Russandol)
Makalaurë/Kanafinwë/Kàno = Maglor
Tyelkormo/Turkafinwë/Tyelko/Turko = Celegorm
Carnistir/Morifinwë/Moryo = Caranthir
Atarinkë/Curufinwë/Curvo = Curufin
Pityafinwë/Ambarussa/Ambarto (Umbarto)/Pityo = Amrod
Telufinwë/Ambarussa/Telvo = Amras (epessë: Minyarussa)
Tyelperinquar = Celebrimbor
Nolofinwë = Fingolfin
Findekàno = Fingon
Irissè = Aredhel
Arakàno = Argon