I have an RP concept in mind involving the Reborn Lineage and a Sorlock made from the combination of the Divine Soul Sorcerer and the Celestial Warlock.    I'm loving the narrative of a Half-Elf who was raised to be Cleric but threw a monkey wrench into things by manifesting Divine Soul power and later falling in battle only to be raised (where Reborn comes in) by a Celestial power who has plans for the character.

That said, it's not necessarily the best mechanical combination (though it brings a lot of tools to the table in my opinion).

Ultimately I want the character to go Pact of the Tome to add supercharged ritual casting to their tool box.  Otherwise, I'm pretty open to what to do with this.

If you had to play this Reborn character, starting at L1 Divine Soul / L2 Celestial Warlock how would you build it?  What choices would you make?  What suggestion do you have (other than play something else 😎)

You are going to be a crazy healer.  So commit to it.  Get herbalism proficiency to start.  Maybe medicine (though it’s mechanically bad).

if you want to take on a challenge, you could be a partial or full pacifist.  By partial I mean that you might pledge not to kill sentient life or humanoids, but would kill monsters, etc. If your DM is willing to play along maybe they’ll let you flavor your Eldritch Blasts as only doing nonlethal damage, like a phaser on stun.  Or go full pacifist and never kill anything.  Only cast buff, debuff, control, and support spells.  Only fight with nets if you aren’t casting.  

That is one direction I plan to go.  I'm likely taking the Healer background from DDB that gives Medicine, Nature, and Herbalism Kit proficiency.  It also has a feature of granting advantage on Medicine checks to diagnose.

Additionally, it looks like our DM for our next campaign will be giving us a free feat.  If that happens I'm going to double down on his mundane healing side by taking the Healer feat.

I see this guy as having been a natural at mundane healing in his youth, which was part of his early training.  His piety might have been questionable, and he might not have been the best student, but he had a knack for Medicine.

As for the pacifist side, I already see him as someone with poor social skills (not willing to participate) who "doesn't want to be here", but was put on this path with the party by his Patron.  Playing him that way without it becoming repeatative or annoying for the rest of the table is going to be a tough enough balancing act I think.   That said, it's definately an interesting angle.

Have you heard of the baelnorn or The Undying Court from Eberron? This reminds me of both of those.

I don't know much about Eberron, and haven't heard of those.  I'll try to check them out.

I have a character that will be following a somewhat similar vein in build, if a very different storyline.  He started his life as an adventurer by gaining a pact, to make up for being physically weak and wanting to have some sense of power.  At level 4, when he hits 5, his innate magic manifests, and his patron advises he is reluctant to offer any further boons, as his bloodline is from a more powerful entity.

That out of the way, theorycrafting (building up levels on the character in the character builder) I find him to be an amazing buffer/debuffer/healer with enough blasting ability to still contribute to combat on both ends.  Metamagic will have him able to Haste or Shield of faith a pair of companions if needed, among other things.  Yes, spell progression is slower, so the BIG spells won't come until later than a pure class, but the versatility of metamagic and upcasting lower leveled spells, I feel, offsets it well enough.  IMO, it's a really interesting multiclass option, with a ton of options.

Tactically, you're going to have to decide whether you want to be primarily a Warlock or primarily a Sorcerer. I'm of the opinion that you'll get more use out of Divine Soul Sorcerer long-term than Celestial Warlock... the biggest downside is that you don't get very many uses of your Healing Light, but that's made up for by your decision to focus on multiple sources of potential healing in your character build. I feel that sacrificing that is far outweighed by Divine Soul's ability to pull from both the Sorcerer spell list and the Cleric spell list, meaning you're going to want to get as high in that class as possible to take advantage of all those options.

With that said, I think you should only take Warlock to level 3 to get Pact of the Tome and the Book of Ancient Secrets invocation. As for your other Invocation, I think it depends on what would work best for your group, but a safe bet is always Agonizing Blast to make sure that you're still fully capable of keeping up with damage output in moments where you don't need to do any healing or support. Eldritch Mind is also a safe bet, as focusing on more support spells will also have you needing to keep up concentration.

At that point you will have two second level spell slots that recover on a short rest, which can be incredibly useful since you can still use them to cast your Sorcerer spells, or convert them into Sorcery Points. For your metamagic options a lot of it depends on what you want, but I think one you're definitely going to want is Twinned Spell. This gives you the option to not only attack multiple targets at once with some spells, but also lets you double down on support spells cast on your allies, and even healing spells... now with a sorcery point when you cast Healing Word you can heal two allies at once. The other metamagic I would recommend is Quickened Spell... especially if you choose Agonizing Blast, no matter what you cast on your turn you'll still have the option to quicken Eldritch Blast and dole out some extra damage. 

Quote from GideonHawke >>

I have an RP concept in mind involving the Reborn Lineage and a Sorlock made from the combination of the Divine Soul Sorcerer and the Celestial Warlock.    I'm loving the narrative of a Half-Elf who was raised to be Cleric but threw a monkey wrench into things by manifesting Divine Soul power and later falling in battle only to be raised (where Reborn comes in) by a Celestial power who has plans for the character.

That said, it's not necessarily the best mechanical combination (though it brings a lot of tools to the table in my opinion).

Ultimately I want the character to go Pact of the Tome to add supercharged ritual casting to their tool box.  Otherwise, I'm pretty open to what to do with this.

If you had to play this Reborn character, starting at L1 Divine Soul / L2 Celestial Warlock how would you build it?  What choices would you make?  What suggestion do you have (other than play something else 😎)

1. Since you've doubled up on ways to be a cocainelock, you should commit.  The basics of that for you are:
   1. Font of Magic:  Minimum 7 levels of Sorcerer or 5 levels with the Metamagic Adept feat (assuming your DM house-rules the feat to actually function, i.e. it needs to raise your cap by 2, not just give you 2, or you can't hold the 2 it gives you) so you can legally hold enough sorcery points at once to make an L5 spell slot with Font of Magic.
   2. Greater Restoration, which is dealer's choice of 9 levels of Sorcerer or Warlock for you, i.e. Sor 7/Lock 9 does it or Sor 9/Lock X does it.
2. As a cocainelock you want nothing to do with Sorcerer 18, as your subclass feature is long-rest based, and equivalently you have particularly little use for Warlock 1 (but you already have that) or Warlock 14.  Sorcerer 17 gets you L9 spells and Warlocks have a very natural stopping point at level 3 anyway, so that's my recommendation: get to Warlock 3 then put all other levels into Sorcerer.