Having a romance with a deity would be a dream come true, right? Even if you are basically an amoeba compared to said deity's powers over ''the elements''? Even if said deity has family, friends, and potentially enemies with similar cosmic abilities (some of whom might not welcome your presence, and can make you their CosmicPlaything if they so desire)? Even if said deity might act as sort of a WeirdnessMagnet beacon to various FairFolk, [[OurDemonsAreDifferent demons]], and [[OurGhostsAreDifferent ghosts]]? Well, nightmares are a type of dream.

* As stated above, Belldandy may seem to be the ideal girlfriend; beautiful and kindly. But consider that she literally controls part of the universe's elements, and possesses immense power as a result. If the thought crossed her mind, she could kill Keiichi or make him suffer a FateWorseThanDeath with just a flick of her wrist, as could her divine sisters and comrades. What would happen if her and Keiichi's relationship somehow [[LoveHurts went]] [[WomanScorned sour]], or, for that matter to any other mortal who came between her and Keiichi? We get a hint of this a couple times when [[ClingyJealousGirl other girls get too close to Keiichi]] and when people [[MamaBear threaten him]]; she suffers PowerIncontinence that causes lightbulbs to explode and freak weather changes, preceded by a DeathGlare that even frightens her father, ''the Almighty''. Simply put, [[YouWouldntLikeMeWhenImAngry you probably wouldn't like]] [[BewareTheNiceOnes Belldandy]] when she's angry. Couple this with all the times throughout the series when Bell's family, colleagues, and enemies who follow her to the mortal realm actually do put Keiichi, Nekomi, and even ''[[ApocalypseHow Earth itself]]'' in much more immediate danger, and this is one relationship which, however heartwarming, incurred a ''lot'' of baggage.
** On top of that, as noted during the Nifelheim arc, she and the other deities are not the {{Bishoujo}} they seem to be, but gigantic {{EldritchAbomination}}s adopting AFormYouAreComfortableWith.
* Hild manages to be downright terrifying by simply changing her tone of voice and adopting a SlasherSmile. The anime even punctuates this with GlowingEyesOfDoom.
* Mara's first appearance in the anime and manga (in a dream of Keiichi's) as a horrifying lich certainly qualifies. So Mara is literal in-universe Nightmare Fuel.
* The "Dream Castle" arc of the manga had some rather spooky-looking ghosts, and Keiichi himself made some wild facial expressions.
* Then there was the Shinnentai spirit, ''especially'' while she was hovering over Keiichi's bed.
* In a more realistic tone, Toshiyuki's attempt to force himself onto Belldandy (and later Skuld in the anime) can come off as extremely unnerving. Thank god that the girls he goes after are prepared to deal with scum like him.
* During the Niflheim arc, Mokkurkalfi warns Keiichi (who'd already defeated three demons, her included, by outsmarting them) to remember his place. She then unveils her true form – an EldritchAbomination enveloping the room. It's pretty terrifying to see, not least to poor Keiichi, who nearly goes insane from fright.
* It's not as flashy or as overt as some of the examples here, but, TheReveal that there's an InUniverse reason as to ''why'' [[CannotSpitItOut Keichii and Belldandy haven't gone any further than the most innocent interactions]] for years of in-universe time [[ComicBookTime (decades of real time)]] – When Keichii made his wish, Heaven basically {{Mind Rape}}d him so that he'd never be capable of considering anything deeper than that. Belldandy ''knew'' this the entire time, but gladly let it continue, because she didn't want to face the consequences of going any further than that. Between the mental image of being under such an effect, and the glimpse into the darker side of Heaven and Belldandy herself, it's really quite chilling.
* The tale of the Lake Goddess counts as both Tear Jerker and this. When her mortal lover the bard dies of old age, she quickly loses her marbles due to grief and demands to be able to see the ocean he sang about, even though she's bound to the lake forever. As her sanity slips away, she uses the HonestAxe scenario (of which she is the arbiter) on ''herself'' to obtain the very sharp axe, then hacks away at the spiritual shackles binding her to the lake. Once she sets a single foot outside her domain, Tyr punishes her by locking her away to drown in her own sorrows for all eternity. Worse yet, Keiichi and Belldandy are forced to experience this story from the perspectives of the participants… so Keiichi gets to feel himself grow old and die, while Bell feels the goddess self-destruct from grief and then watch helplessly as her own father locks the poor goddess in a cocoon until the end of time.
* During the Final Race, specifically the end of Attempt No.2, Keiichi ''dies''. Literally dies. As in, he felt his skull shatter and nearly every bone in his body break before tumbling off the road into the abyss. When he asked Tyr if it had all been a trick, Tyr replied it ''wasn't''; Keiichi really had died. Well, technically, Tyr stepped in at one millisecond ''before'' Keiichi died and rebuilt him. But it's close enough to be beyond terrifying to contemplate. Worst yet, since Keiichi had already failed twice, Tyr heavily implied he wouldn't step in to help if Keiichi screwed up again.

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