The first incarnation shown (in the screenshot with the Sarafan stronghold backdrop) appears to be younger, and shares many similarities with the Kain of Blood Omen 2, specifically the pale white pigment, human-like digits extending into blackened claws, and very similar facial features. The main changes are with his clothing and hair; he now dresses in a uniform that appears to be a very early version of his Soul Reaver costume, and his hair is longer and tied at the bottom. The increase in hair length would suggest that some time has passed since the events of Blood Omen 2.
The second incarnation (shown in the concept piece) seems to be a later stage in the vampire's evolution. Kain's hands and feet have fully transitioned into hooves and talons, his facial structure appears to have changed significantly, and the pigmentation of his body has taken on a dull amber colour. This change in pigment could perhaps be the start of his growth of the dermal shell that has fully replaces his skin by the time of Soul Reaver.
Given the ambiguity of whether Raziel was intended to be a playable character in The Dark Prophecy, the appearance of these past incarnations of Kain in the media further convolutes our understanding of the game. A few possibilities can be suggested:
For a number of reasons, the idea of the younger Kain(s) being playable seems unlikely. Consider that The Dark Prophecy appears to be heavily based on the design of Defiance, which alternated between two characters with similar mechanics and powers. The younger Kain's limited powers and agility would juxtapose unfavourably with the elder Kain and Raziel, leading to some jarring gameplay as the game shifts to a comparably underpowered character. The popular and marketable Raziel would also, from a financial if not narrative perspective, make more sense as games featuring his character have always been the more financially successful of the series. The idea of jumping between three (or more) playable characters may have fragmented the experience considerably.
A scenario that seems logical given the limited media is that Kain (and possibly Raziel) were to remain the series' protagonists, with the younger Kain(s) being shown in flashback sequences to provide story elaboration. This idea could explain the differences in the designs, with one Kain being clearly at a later point in his vampiric evolution, and therefore from a later flashback.
Such theoretical flashbacks could perhaps be triggered through environmental prompts, with the elder Kain perhaps seeing a location or event that reminds him of his younger days. The game may then give us a brief flashback (overlaid by a reflective monologue by Kain perhaps) that serves to expand the series backstory while also providing information relevant to Kain's present quest.
Here is a possible example: In the various media there is significant evidence that Malek's Bastion was to be an early level in The Dark Prophecy, and some evidence suggests that Dark Eden could have followed soon after. In between these two locations on the original Blood Omen map is the Oracle's Cave.
While journeying from the Bastion to Dark Eden, the elder Kain may pass the entrance to the Oracle's Cave. This could then trigger a flashback sequence to the moment his younger self ventures beyond the Oracle's Chamber and discovers the Chronoplast, the moment he first began to understand that "free will is an illusion". We could even observe in this flashback sequence the moment that Kain learns he may be the Scion of Balance, perhaps with further elaboration provided on what this role actually is.
The potential for further flashbacks is significant. Kain could see Vorador's Mansion in the distance, and flashback to a moment in which his younger self somehow resurrected the ancient vampire. He could pass the Sarafan Tomb, and we could see the process by which he resurrected the no-doubt heavily decayed corpses of the Sarafan and transformed them into his vampire children. A return to the Sanctuary of the Clans could prompt a flashback to the uncomfortable time immediately following Lieutenant Raziel's shocking and violent execution, perhaps exploring the fate of the Razielim clan.
There is the possibility that the young Kain of this era could appear in person, appearing immediately after the destruction of The Pillars (which has only just occurred in the time period the elder Kain currently occupies). There may be an untold adventure to tell, something that the young Kain experienced before his invasion of southern Nosgoth (the onslaught depicted in the Blood Omen 2 opening cinematic).
If this younger Kain somehow interacted with the elder Kain or Raziel, it would certainly be interesting to see how such a meeting could proceed without damaging history. Perhaps like with Ariel's interactions with Raziel in Soul Reaver 2 and Defiance, the Kain of the past would simply regard his older self and Raziel as being demonic thrall.
The appearances of the two Kains in the media do not support this possibility as much as they support the flashback idea. Features of their designs, in particular their transitional evolutionary traits, suggest that both come from a period following the events of Blood Omen 2.
Regardless of how this young Kain appeared, either in person or through flashbacks, it appears that some of Kain's earlier experiences may have been vital to the narrative of The Dark Prophecy.
Comments From Ben Lincoln
A nearly-identical version of Daniel Cabuco's "Young Kain" concept art made a cameo appearance a few years ago on TLW, when I discovered it hidden in the data files for Defiance (as a temporary placeholder for the portrait of Kain in the Mausoleum) - see the Only Skin Deep article for a few more like this.
However, as Divine Shadow pointed out when I sent him that image, there are some notable differences. Was there a series of art depicting Kain's evolution in stages? If not, is the larger image from the beginning of this article older or more recent?
Given what has been revealed about The Dark Prophecy (especially Ranjeet Singhall's screenshot), I could easily see this as being something that was originally intended for Defiance, but bumped out to the unfinished sequel due to time constraints. This is difficult to reconcile with a non-player character list for Defiance that doesn't include such a character, though, unless that list had been revised to exclude him, or if he was intended to only appear in artwork, not as a principal character.
The screenshot was found in the now-inactive portfolio website of Ranjeet "Rungy" Singhall, a former Ritual Entertainment developer. Ranjeet's website was previously located at http://rungy.us/, but the domain registration has expired.
The image was accompanied with the following explanatory note:
A redesign I did of Kain. Of all the IP's I have worked on I have never recieved as many personal emails regarding any of them as I do with Kain. Eidos has not commited to another installment of the Legacy of kain series which I consider to be a serious mistake. There's a rather large and deicated audience to this IP.
— rungy.us [no longer available]
Elsewhere on the site, Ranjeet explained his role on The Dark Prophecy.
Legacy of Kain Ritual/Eidos/Crystal Dynamics
Director of Art and Animation Technology
Created and documented all Art Dept production processes. Worked with Crystal Dynamics to finish and ship Legacy of Kain Defiance and we did about 6 months of work on a sequel before it was cancelled by Eidos. Mostly art tech tasks here, pipeline debugging, Mel script support for character pose pasting and rig setups.
— rungy.us [no longer available]
The concept artwork comes from the portfolio of former Crystal Dynamics staff member Daniel Cabuco, who worked on the series from Soul Reaver through Defiance as well as several of Crystal Dynamics' Tomb Raider titles.
The image of "Young Kain" is not cited as being for or from any particular game, but evidence suggests that it was not intended for Soul Reaver 2 or Defiance. An accompanying piece of artwork (for Kain's "Dire Wolf Form") is dated with the year '02, suggesting the pieces were created significantly into Defiance's development, at a time when the game would have possibly been beyond initial character concept proposals.
During these essays, contact was made with a source who has asked to remain anonymous, but has been confirmed to have worked on Defiance and The Dark Prophecy. The source was not at liberty to give too much information, but did share Defiance's NPC (Non-Playable Character) list from its initial design document. This list confirms that at no point in development was "Young Kain" intended to appear in that game.
We know from Isabelle Lemay's portfolio (another former Crystal Dynamics staff member), that some of Crystal's staff worked with Ritual Entertainment on the initial stages of The Dark Prophecy. The Google cache version of this page is still available, even though it is no longer present on her website.
Though there is no official confirmation, it seems a likely possibility that Daniel Cabuco's "Young Kain" concept piece was indeed intended for the cancelled game.