Which operators break the general pattern for DP cost progression?

In the hero-collector tower defense game Arknights, each Operator (unit) has a DP Cost, which can change as the unit is enhanced/developed by the player. Most Operators follow the same pattern:

• As new units, they start with some specific DP cost (let's say 16, for example)
• Promoting the unit to Elite One rank increases their DP cost by 2 (to 18, in our example)
• Increasing the unit to their maximum Potential grants two separate DP cost reductions of 1, for a total of -2 (back down to 16)

Units of at least four-star rarity can be promoted a second time to Elite Two rank, but this generally does not affect their DP Cost. Therefore, a fully maxed-out unit usually ends up with the same DP Cost as when that unit was brand new.

However, there are exceptions to the pattern. Some examples:

• Saria incurs an additional +2 to her DP Cost upon promotion to Elite Two rank, leading to a final DP Cost higher than her initial cost
• Grani benefits from three (rather than two) -1 DP Cost reductions when maximizing her Potential, leading to a final DP Cost lower than her initial cost
• Fang gains a Talent upon promotion to Elite One that reduces her DP Cost by 1, also leading to a final DP Cost lower than her initial cost

Which other Operators break from the pattern described above, and in what ways?

Here's is a list of operators that break the general pattern for DP cost progression

The operators are grouped by their type and sorted by rarity (indicated by [#] before their name) in a descending manner:

Vanguards

1. [5*] Zima: her E1 Talent reduces her DP cost by one (1)
2. [5*] Grani: her Potential reduces her cost by three (3)
3. [3*] Fang: her E1 Talent reduces her DP cost by one (1)

Defenders

Note: All Defenders gains two (2) more DP cost when promoting to E2

1. [5*] Bison: his Potential reduces his cost by three (3)

Specialists

1. [5*] Snowsant (CN only): her Potential reduces her cost by three (3)
2. [4*] Gravel: her E1 Talent reduces her DP cost by one (1)

Medics

1. [5*] Ceylon: her Potential reduces her cost by three (3)

Snipers

The following operators gains two (2) more DP cost when promoted to E2:

1. [6*] W (CN only)
2. [5*] Meteorite
3. [5*] Provence
4. [5*] Sesa (CN only)
5. [4*] Shirayuki

Only one Sniper operator benefits from DP reduction from her E1 talent:

1. [3*] Catapult

Guards

The following operators gains two (2) more DP cost when promoted to E2:

1. [6*] Blaze
2. [6*] Ch'en
3. [6*] Hellagur
4. [5*] Bibeak (CN only)
5. [5*] Broca (CN only)
6. [5*] Savage: she also has no DP reduction from her Potential
7. [5*] Specter
8. [4*] Cutter (CN only)
9. [4*] Estelle
10. [4*] Utage

The following operators benefit from having three (3) DP cost reduction from their Potential:

1. [5*] Flamebringer
2. [5*] Sideroca (CN only)

One operator does not have any DP cost reduction from their Potential:

1. [4*] Conviction (CN only)

All of these data is accurate as of 1st of June, 2020

Source: Aceship's Operator Details