It's probably best to use an Altmer.
*conjures Hevnoraak* it may take some time for the spell to work
Hevnoraak sees all, my child.
But I second Altmer; they're naturally closer to what the Falmer would have been, lore-wise. And they can worship any Daedric Prince you fancy, as their pantheon was entirely Aedric, and any Daedra worshippers would have been outliers. Given the character of the race, though, Azura or Hermaeus Mora seem appropriate.
Sooo, your name is Otar? In that case, he ain't Hevvy...
*puts on shades*
...he's your brother.
oh this should be good. Otar needing help from Hev?
*hears name chanted in unison several times in a row*
Taaaahrodiis Joorre... WHO summons me?!
Ah, Otar. It's been too long.
Some inspiration:
1.) http://cloud.steampowered.com/ugc/541833502858236844/1B847B68AFE8FF274558810A8368701C2B4140DB/
2.) http://cloud-2.steampowered.com/ugc/541833502858240741/74D48634DBD050FAF78616804F9CF2EC17CF8864/
3.) http://cloud-2.steampowered.com/ugc/541835583571114210/5B6F58EA01DE83724E0E55B0F5F525A3BE86DD82/
4.) http://cloud-2.steampowered.com/ugc/577864844271411820/6E35AF9233F7DB7411AEA8151A97CC178BA1E864/
5.) http://cloud-2.steampowered.com/ugc/541835583571095320/D2889517201C65AB30D567AB2A7B46CCEA210740/
6.) http://cloud-2.steampowered.com/ugc/577864844271191501/CC1D89A46BBBFE3948A7BE8712E7C4E1D23E1B5C/
7.) http://cloud-2.steampowered.com/ugc/577864844271838358/CAD0A8169FFB61BD7C11048C5FEE278E09286D3F/
Behold, the return of the Snow Prince!
8.) http://cloud-2.steampowered.com/ugc/578991472819355383/0103EF7DA67A7BC8D79963AC9929BB4D82063CFC/
9.) http://cloud-2.steampowered.com/ugc/578991472819359411/0D3DFD921C7D5EF39FC1E14F877C2DB8B9FEDB01/
10.) http://cloud-2.steampowered.com/ugc/578991472819364293/34B581727D292EE72ACD51D53AC190F857D9ACC4/
11.) http://cloud-2.steampowered.com/ugc/541834765411947036/70FA1E3D9930185BC8648EF597AB0F6DA8A7E953/
12.) http://cloud-2.steampowered.com/ugc/541834765411954081/5BFA28E38CDB4721E2A0E4D146E090298BE122D9/
13.) http://cloud-2.steampowered.com/ugc/541834765411961870/DEEE288D9172F931AA68722D5D3F65B7245E382C/
This Nord....
14.) http://cloud-2.steampowered.com/ugc/541835583571057551/4ECDC41B708F16813EA0940AC62C7F275D8A04BF/
15.) http://cloud-2.steampowered.com/ugc/577864844201885444/50C4B5DBFB13F5D3D5367AB56191F9426BA954B6/
16.) http://cloud-2.steampowered.com/ugc/541835583571072806/02A71F465A5611BD3223B3ED5D4450C01EB48612/
17.) http://cloud.steampowered.com/ugc/577864844201854332/D012E8A10D2582C032E6D412A79110F6EFD46195/
and this was just the intro...
http://cloud-2.steampowered.com/ugc/578991472936612024/723A433879A832C1BA971A2220D647C463DF998A/
For 4,000 years you have suffered from their genocide. Their wholesale relentless slaughter. The unquenchable blood-thirst of those barbarians. Those children of the enemy. Auri-El warned us to be wary of them. And what did we do? We ignore his warning, and welcome these Atmorans with open arms. Then the Night of Tears...
There are but many myths and little fact on just what happened on that faithful day. But the results of it were real. The blood-thirsty demons returned from their hell with an unyielding blood-lust. Auri-El's champion, savior and messiah of the Falmer - http://cloud-2.steampowered.com/ugc/542959956154204150/A14E4E9BF3BF20D2B8AFC672B1ADA2E17413BD9B/ he is known as. With the wildest of bad luck, he fell in battle from the most unlikely of sorts, in the most unlikely of ways. And from there on, the Falmer were as good as dead. Many fled for their lives, many stood their ground and accepted their death, and many surrendered. All of them would suffer. And the Falmer would suffer for the rest of time, from their children, http://cloud.steampowered.com/ugc/578991472937216962/22F4F89F7AFA8E99C86408E4503FBD161825C516/
The Betrayed, for betrayed they were, by the treacherous, selfish Dwemer... http://cloud-2.steampowered.com/ugc/577864844275665379/F14A51B51BB188170EF8B8410366AD4DB37A5F06/, and without proper guidance. http://cloud.steampowered.com/ugc/541833502892275488/935AAF0D229223917EF9EE72D55F6BDDB3D4F16C/ There is but http://cloud.steampowered.com/ugc/578991472937290749/B26A7F06C279D06B797E894219A40D060A91EE42/ who can http://cloud-2.steampowered.com/ugc/578991472937233906/365959E7F7B75B994BD1A483574016B93521FACC/ Who can guide the fallen Falmer back to the http://cloud.steampowered.com/ugc/577864844162982693/CAFD4EA6B844348F7C944F6B1746C6504F66D699/ One, who brings the Betrayed into unison and purpose...
http://cloud-2.steampowered.com/ugc/578991472936704456/78FB967E550D7FD04AF3E5F93D10AF7625AB926B/
http://cloud-2.steampowered.com/ugc/541835583545865106/1CE1DA21D5302215B2371F56D1C19211C627844D/
And so, with Malacath's vengeance in his mind, and anger in his heart. The reincarnation of the Snow Prince began his http://cloud-2.steampowered.com/ugc/578991472936620586/496C3AAD5FD020BA586FE2616FAF9C7E15130371/ The ancient city... built by Falmer enslaved by Ysgramor and his devil horde. http://cloud-2.steampowered.com/ugc/578991472936617262/C3660B0AF683482C8F9AB6DC5CBFD534F3108E8F/, the Nords - obsessed with fighting amongst themselves - never expected. So fierce was the attack, http://cloud-2.steampowered.com/ugc/578991472936627857/26D4FB406A2A7EDC9D8733E151398B14B25B07F1/
And the Betrayed called out to their savior: http://cloud-2.steampowered.com/ugc/578991472936632751/2A667984EABCC7EDB997B8B2ADB3F22CCEFF2CCD/
http://cloud-2.steampowered.com/ugc/578991472936719529/0D92C47E2267BCE32E98F858B8B3686174E1C05F/
And the Snow Prince http://cloud-2.steampowered.com/ugc/578991472936697176/05EC9614CFAF1702C1353F185D23129963FD5427/ for Auri-El has shown him the way. All the anger, misery, and suffering the Betrayed endured, was all but http://cloud-2.steampowered.com/ugc/578991472936725701/0587E26AEDD2DC9ECEEF0680CB9FABFBBAEA3312/
"http://cloud-2.steampowered.com/ugc/578991472936644568/1E5BC1FC0DE784B092608C067F6F05308F4859F7/ that rends travelers http://cloud-2.steampowered.com/ugc/578991472936662125/A48E8759E2B0DE6A5BF1C6E69756C12BC8019C36/ loose the very foundations of the sturdiest hall, the http://cloud-2.steampowered.com/ugc/578991472936666868/9877986291143CAE7327539E19A823C2D1222ADA/ Indeed the ice and snow did begin to http://cloud-2.steampowered.com/ugc/578991472936732011/74EC6A1CD74AD23888CDE2CF0F16533C7A7B9A99/"
"http://cloud-2.steampowered.com/ugc/578991472936754117/7432B20AF9BA4E0336CBD657888C22E82E1A8B01/
http://cloud-2.steampowered.com/ugc/578991472936828203/D2BF44E16FF9F6570673A555C0EB2BA4F5446E38/
http://cloud.steampowered.com/ugc/578991472936831943/6AA513FFA96ACBC6EE2C5AA134550DF8DED14A0C/"
That day... Auri-El shed a tear, and Sovngarde shook.
http://cloud-2.steampowered.com/ugc/578991472936846328/0D998C84736E31FE6A48C52649968AF86E9FE5D4/
http://cloud-2.steampowered.com/ugc/578991472936850228/C24170CA01A90B0A4E66F76D320AA4E81157CBC7/
http://img.photobucket.com/albums/v730/ZoDiaC91/044b554e-8562-47d1-a64b-ea45391bdb1e_zps0ea1ea07.jpg?t=1371005016
Be sure to take notes!
Now, before I can provide help... Are you on PC or console?
It's still do-able. But it's impossible to look like a Falmer. The palest mer are the Altmer, and they cannot get as pale as a Nord or Breton.
As an alternative, you could role-play an Altmer who feels vengeful sympathy for the Falmer. Finds Gelebor and the statue of Auri-El. Receives a *vision* from Auri-El. And decides to act in Auri-El's name to take on the burden of hate, and avenge the Falmer yourself. Wear snow elf armor along with Auri-El's shield and bow.
Daedra are a big no-no. Falmer were much like the Altmer. They were the closest of kin.
Feel free to summon Frost Atronachs though! The Falmer likely did it. You can summon lesser daedra, as long as you use them solely as tools.
Mostly warrior. But is more then willing to supplement his melee combat with some magic. Think of a battle-mage, but with a focus on melee. Use my Snow Prince as an example: Elegant, fierce, and majestic. He'll usually start combat by summoning a frost atronach, and then popping a frost cloak while throwing a few Ice storms/spears. Then depending on the enemy[the enemy's fighting style and distance] either switch to his sword and Auri-El's shield, or Auri-El's bow. He also uses wall of frost in conjunction with his sword every once and awhile.
I can get you some more pictures of him and his fighting style if you'd like, but what I posted above in spoilers should give you a good idea.
I'm assuming your not on pc so I would also go with an Altmer as they're closer to Falmer and simply explain away his appearance and being treated as an Altmer as an Illusion spell working splendidly.
As he'll be a battlemage I suggest specializing in Ice spells and also using the new sun spells added by Dawnguard.
Meh, I find that cheap and a stretch. A sympathetic Auri-El gung-ho Altmer with a chip on his shoulder for humanity, works fine.